What it means
In UK chat, whack pulls double duty. It can mean a quick hit, usually not some dramatic movie punch, just a smack to get a dodgy thing working. It can also mean your share of something, like money, food, or winnings. Bit rough, bit casual, dead normal in everyday speech.
Usage examples
"Boiler’s clunking again, so Gaz says give it a whack. One tap and it behaves. Later he’s like, right, where’s my whack of pizza?"
"The old telly only works if you give it a whack on the side, right where the dent already is."
"Everyone got a fair whack of the winnings, even the bloke who only chipped in a quid."
"Just give the meter box a whack, it only wakes up when you treat it a bit rude."
"You took the booking, I did the lifting, so where's my whack of the money then?"
Where it comes from
Whack is an old English word for a blow or sharp strike, recorded from the early 1700s. The sense of a share or allotted portion turned up later in informal English and stuck in British and American speech, so your whack became your cut of whatever's being handed round.
