Movies were the hot leisure item for Americans last weekend, and no movie was hotter than "Revenge of the Nerds II: Nerds in Paradise." The wimp farce opened in the No. 1 position for 20th Century Fox, taking in nearly $8 million from 1,351 screens. Stanley Kubrick's "Full Metal Jacket" soared to the No. 2 spot, scoring the highest per-screen average ($6,901) with grosses of $6.1 million from 881 theaters. The news was good for nearly every studio as 11 movies grossed $3 million or more. But the biggest news may have been the comeback of Disney/Touchstone's "Adventures in Babysitting," which rode a new ad campaign and charges of racism to a 43% jump over its opening weekend business. "Innerspace," also benefiting from a revamped ad campaign, showed a 9% increase from its July 4 opening. The only movie people apparently didn't want to see was "The Squeeze," a Michael Keaton comedy that took in just $1.4 million from 1152 theaters.