and then wash your hands

Also lick your lips and show a little teeth. I have a friend who is into bird watching, and apparently the licking of lips is often enough to scare away birds that would otherwise have waited around a little bit longer.

But I don't like making eye contact!!

just throw them away

If I get my hands on one of those things I'm not throwing it away before repeatedly smashing it as hard as I can against the most solid surface I can find in the vicinity. Or against another seagull, if possible.