It's my round
What it really means
In a pub, friends take turns buying drinks for the whole group — each turn is a "round". Saying "it's my round" means "I'll buy this set of drinks". If someone buys you a drink, it is polite to buy one back later.
Context, tips & common mistakes
The round system is one of the strongest unwritten rules of British social life, and misunderstanding it is a genuinely costly mistake. Once you accept a drink in someone's round, you have implicitly agreed to buy one back — leaving before your turn, repeatedly, will be remembered. The polite escape routes are all acceptable: say "I'm only staying for one" when you arrive, buy your own with "I'm not in the round, thanks", or take a soft drink or lime and soda when it is your turn to receive — nobody minds what you drink, only whether you reciprocate. In a big group, rounds sometimes split into smaller sub-rounds of three or four, which is normal. If money is tight, saying so plainly ("I'm skint this week, I'll sit this one out") is respected far more than quietly dodging your turn. The system runs on memory, not receipts — and British memories for rounds are excellent.