"Bring a bottle"
What it really means
House party invitations often say "bring a bottle" (sometimes written BYOB — bring your own bottle). It means bring some drink to share — wine, beer, or a soft drink if you don't drink alcohol. Arriving empty-handed to a bring-a-bottle party is noticed. Your bottle usually goes into the shared pool in the kitchen.
Context, tips & common mistakes
"Bring a bottle" means contribute to the party's communal supply: a bottle of wine or some beers you would be happy to drink, handed over or added to the kitchen collection on arrival. The subtle rule newcomers break: what you bring stops being yours — it joins the pool, you drink whatever is going, and retrieving your unopened bottle as you leave is a small but memorable faux pas.
Calibration: mid-range is fine, nobody inspects labels, and non-drinkers bring soft drinks, snacks or a dessert with identical social credit. Distinguish this from a dinner-party bottle, which is a gift to the host (they may or may not open it tonight, and that is their call), and from "bring a dish", which is the potluck variant where your contribution is food.
Example conversation
What you could say back
No spoken reply needed for this one.