Amanda Peet lives in fear. On the set of A Lot Like Love, a romance of mismatched ambitions and expectations, she did the unthinkable: She punked costar Ashton Kutcher. ''I put shaving cream all over his Escalade. And wrote Punk'd in it,'' says the actress. ''And then I did it again on my last day of shooting.'' She currently awaits the inevitable retaliation: ''The silence is deafening.'' Granted, this was in retaliation for Kutcher TP-ing her yard during a party. ''I was there, and Demi's girls were with me,'' Kutcher explains. He enjoys teaching girlfriend Moore's brood about the finer things in life, including the miracle of two-ply. And besides: ''They were getting bored. That's how I entertain the kids.'' Somewhere in the midst of all this madness, the two managed to shoot a movie ''about two people who love each other but have really bad timing,'' says Peet. ''It's not a very broad comedy. Ashton's so good. I fell in love with him all over again when I saw it. Then I was a little scared that he's so much better than I am. So I went from having a crush on him to feeling really competitive.'' Could this be the greatest punk of all?