Loose change, generally 1p's or 2p's (in UK) which constitute suitable throwing material, used to partially injure and or humiliate disliked individuals.
5 or 10p's can also be suitable to throw for those think themselves as better then the majoity.
1.'Hey I'm sure that pikey over there was givin' me a pedo look, like he wanted to sell me some gypsy pegs or sommat'
'Don't take no stick. Here I've got some shrapnel left from lunch put a hole in his skull!'
2.'Did you hear 'bout Etheridge and the coin incident?'
'Yeah, that was me. I just pinged a peice of shrapnel off and he collapsed about 5 seconds later. He must have been nearly 100yds away!'