i work in a meat processing plant in the canteen one of the jobs is picking up dirty crockery which is beside a glass partition couple of lads was playing a joke on me last night by banging loud on the glass then looking away and giggling this happened a few times the next time i gave them them the flick off sign by rubbing my face with one finger you should have see the shock on the youngest ones face that a old lady my age would use such sign language could nt help laughing at his expression
They were probably expecting you to get indignant. What you did was very funny, because it was unexpected. ;D