Ok, it made me laugh anyway....
Background details: Needed to buy some of those polystyrene packaging chips for our e-bay business at work. I ended up buying a 5 foot tall bag of the stuff.
K, now I've got that out of the way, here's the main point.
Was sitting on the bus with this bag in the pram area (luckily no prams came on, wasn't getting this thing anywhere else).
This guy gets on, chatting away on his phone, my bag of polystyrene things catches his eye.
He stands there for a good minute staring at the bag, plucks up the courage to raise his hand, extend a finger and...
wait for it
prod the bag, before promptly walking upstairs.