It happened again: A presidential tweet hit an entire industry, Jim Cramer told his Mad Money viewers Tuesday. But fortunately, that industry was pharma, and it's created the perfect opportunity for investors to buy, buy, buy.

Cramer said investors have three options when President Trump takes aim at stocks in their portfolio. They can panic, they can take a wait-and-see approach or they can buy on the weakness.

As we've learned with Boeing (BA) , Lockheed Martin (LMT) , General Motors (GM) and countless others, the correct response is to start buying.

This is not the first time Trump has been critical of drugmakers and drug pricing. But the fact remains that to make any substantive changes, the President will need Congress, and Congress' track record against drug companies clearly shows that this is a battle that cannot be won.

Cramer said if Trump really wants to lower drug prices, he should target our trading partners, which squeeze all of the profits out of drug prices for their citizens, leaving the U.S. to burden all of the research and development costs.

That's why Cramer said he'd use today's weakness to buy Merck (MRK) , Eli Lilly (LLY) , Pfizer (PFE) and Allergan (AGN) , an Action Alerts PLUS holding.

Meanwhile, on Real Money, Cramer explains why the FANG stocks (Facebook (FB) , Amazon (AMZN) , Netflix (NFLX) and Google, now Alphabet (GOOGL) ) are still going from strength to strength. Check out his strategies with a free trial subscription to Real Money.

Oh, Snap

If you're a younger investor who picked up shares of Snap (SNAP) , Cramer said he's sorry for your loss. Shares plunged another 10% in today's trading. He said the company's IPO of just 200 million shares had little chance of providing more than a short-term pop, which is exactly what it gave us.

Cramer said he only hopes that the deal, which was immensely popular among younger investors who adore the product, hasn't soured them against owning individual stocks. The truth is that Snap has no plans to turn a profit, has slowing growth, $400 million in annual data center costs and an unproven advertising model.

Snap may be able to reinvent itself as a video provider or the company might benefit from additional advertising dollars moving online, but in the meantime, Cramer said, his daughter informed him that "no one clicks on the ads" in Snapchat, and that should be worrisome for investors once the newness of the company wears off.

Executive Decision: Logitech

For his "Executive Decision" segment, Cramer once again sat down with Bracken Darrell, president and CEO of Logitech (LOGI) , the computer accessory maker with shares that are up 27% since Cramer last checked in back in November.

Cramer first asked how it is that Logitech could deliver a 367% return over the past four years, vastly outperforming the markets. Darrell explained that Logitech is a "humble device maker" that just makes great products that people love. He said his company's keyboards, mice and headsets are beloved by gamers for whom every millisecond matters.

Logitech is also a global company, with its products being sold online and in stores worldwide.

When asked about the future, Darrell said that the cloud is the new growth platform for Logitech and there are many opportunities for new devices to connect to cloud.

Off the Charts: Tesla

In his "Off The Charts" segment, Cramer checked in with colleague Robert Moreno over the chart of Tesla (TSLA) , which has fallen from $280 to $248 a share after hints of a secondary offering began looming.

Moreno noted that Tesla's weekly chart have been moving in 43-week cycles, building towards its highs of $285, then breaking down and selling off violently. The stock's high last month were right on schedule, with the next time to buy likely in November.

The chart of Ford (F) however, has been stuck in a downtrend since 2014, but has recently consolidated and si not near its long-term ceiling. The MACD momentum indicator just signaled a bullish crossover, with the Chaikin money flow nearing positive territory.

Moreno also looked at General Motors (GM) , which broke out in November in a measured move higher, but also has been consolidating. With the MACD and Chaikin both bullish, Moreno felt the stock was a buy above $38.25 a share.

For more on Moreno's examination of Tesla's charts, read Tesla's Cyclical Winter of Discontent.

Executive Decision: Thor Industries

In his second "Executive Decision" segment, Cramer spoke with Bob Martin, president and CEO of Thor Industries (THO) , a stock that was crushed today, down 9.8%, on a penny-a-share earnings beat with tempered guidance.

Martin said they were being conservative in their guidance, but still expect to have an good year, even if production is limited. He said RV dealers have never been more positive and the production increases will happen; they just take time.

When asked about the drop in average selling prices, Martin said they are selling more entry-level trailers and homes to younger buyers, but he sees that as a positive because those buyers will upgrade over time.

Turning to the topic of rising gas prices, Martin said after seeing $4 gasoline just a few years ago, the retail channel is ready for rising prices from current levels. Buyers simply take shorter trips, he explained, and it's not a factor for sales.

Cramer told viewers to do their homework on Thor.

Lightning Round

In the Lightning Round, Cramer was bullish on Treehouse Foods (THS) , TG Therapeutics (TGTX) , Kinder Morgan (KMI) , Magellan Midstream Partners (MMP) , Chesapeake Energy (CHK) and Arconic (ARNC) .

Cramer was bearish on Exact Sciences (EXAS) and Stratasys (SSYS) .

Read more of Cramer's comments about the stocks in the Lightning Round.

Cramer and the AAP team say news and caution are weighing on energy and health-care sectors. Find out what they're telling their investment club members about Apache (APA) , Cimarex (XEC) , Arconic (ARNC) and Allergan (AGN) with a free trial subscription to Action Alerts PLUS.

Trump and your taxes: Cramer leads a roundtable discussion on how investors and retirement savers should position their portfolio.

Search Jim Cramer's "Mad Money" trading recommendations using our exclusive "Mad Money" Stock Screener.

To watch replays of Cramer's video segments, visit the Mad Money page on CNBC.

To sign up for Jim Cramer's free Booyah! newsletter with all of his latest articles and videos please click here.

At the time of publication, Cramer's Action Alerts PLUS had positions in APA, XEC, ARNC, AGN, FB, GOOGL, MMP.

More from Jim Cramer

Total SA, Bluebird Bio, U.S. Silica Holdings: 'Mad Money' Lightning Round

Total SA, Bluebird Bio, U.S. Silica Holdings: 'Mad Money' Lightning Round

The Bears Have it Backwards: Cramer's 'Mad Money' Recap (Monday 9/24/18)

The Bears Have it Backwards: Cramer's 'Mad Money' Recap (Monday 9/24/18)

Monday Madness: Nike Just Does It

Monday Madness: Nike Just Does It

'The Economy Is Quite Strong,' JPMorgan CEO Jamie Dimon Tells Jim Cramer

'The Economy Is Quite Strong,' JPMorgan CEO Jamie Dimon Tells Jim Cramer

Jim Cramer: Be Careful in the Cannabis Stocks

Jim Cramer: Be Careful in the Cannabis Stocks