Acting on Impulse

Ok so today in Spanish we had to go around and write our name down on like 7 peoples papers so we would be their partner sometime. Well, I was sitting beside my crush and he wasn't there so i decided to put my name down on his paper. He came back in the middle of the class and we had to go through everyone's partners. Well, when I told him I was one of them he looked at me funny. Now i feel like a idiot! Acting on Impulse sucks. What thing did you do on impulse that you consider stupid or you regret?