Got caught masturbating how to deal with it?

I was with some friends after school to go hang out and while we went to a music store to look around... there was a poster of Avril Lavigne in the rack and she's like...amazing. I could not stop thinking about her so when we left..i said i was going to just head out. went back to the store and bought the poster then i had this idea to masturbate to Avril in a park. i went to a quiet spot and unrolled the poster and started masturbating. i was getting close to shooting and called out her name a few times and as i started to come a few other people from walked by and saw me with the Avril poster. they were all laughing and now what if they say something at school? what can i do to avoid them.