TheStreet's Action Alerts PLUS Co-Portfolio Manager Jim Cramer says Facebook and Under Armour are both great technology stocks. Under Armour is a stealth tech company because it is reinventing apparel and the company's sales spike in cold weather. Cramer says Facebook is trading "dirt cheap" for a growth stock and this is the time to buy. However, Cramer doesn't like Exxon Mobil, which he says would never have gotten to $90 if Warren Buffett hadn't made an "ill-timed" buy. Cramer says Exxon's lack of production growth in the most recent quarter makes him a believer in the independent producers Noble Energy and Continental Resources.