Anything worth doing is worth overdoing. I'm not sure if this holds for Larps, but in a short plays, it has to get obvious. Shuffle those feet. Laugh at inappropriate moments. Run to get the door for someone. Make bad attempts to impress people. Step aside when someone walks past you. Get clumsy or hyperactive around someone. Say stupid and inappropriate things. "I'm not in love with you or anything, really, not me, no sir."

There are lots of geek heroes in 80's movies. Take their most hopeless moments and make them yours.