doing an andy

jizzing your pants when a girl touches you on your thigh, preferably the new girl to your school.

(on the coach, she gets up to leave, touches his leg as she gets off)
andy: oh dear, things have got sticky....
girl: i've caught you doing an andy! keep up the good work

to do the andy

To ask a pretty woman you happen to meet on the street for a drink

Wow that girl is cute!" - "Are you going to do the andy on her?" - "Yeah, I should