"Tonight it's time to attack enthusiasm," Jim Cramer told viewers of his "Mad Money" TV show Thursday. While Cramer said he enjoys enthusiasm, if market players want to make money, they must "check their enthusiasm at the door," he said. Taking Global Sources ( GSOL) as an example, Cramer said that when he mentioned it as a buy last week, the stock "went up huge" immediately after hours. He urged people not to buy after hours, advising them to take a day to do their homework on a stock before buying it. J. Crew ( JCG) spiked after it reported its last quarter, but as it was likely that the stock would make its way down again, Cramer said this is the type of enthusiasm people should have sold. After waiting for a pullback from J. Crew, the market finally got one Thursday, he said. The retailer closed that day at $39.99, and Cramer believes it's time to pull the trigger on this stock -- but not all at once, he warned.