You might 'click' immediately and they could become the love of your life - or you might never see them again.
But either way, at least you've got a free drink out of it, right?
One student who was bought a drink for being "gorgeous" was shocked when she received a text two weeks later asking for a refund.
Abby Fenton, 18, was out in Sheffield celebrating her last few nights at home before starting university when a tall man approached her.
The teen, who is studying Biomedicine at Leeds Beckett, said that the stranger offered to buy her a drink in Viper Rooms, Sheffield, before walking off.
Two weeks later, she got a text off an unknown number...
But her photo of the exchange has gone viral on Twitter, so Liam is probably feeling a bit sheepish.
Abby, from Barnsley, said: "I was at the bar about to get myself a drink myself when he came over to me and said: 'I'll get that for you, you're gorgeous' and all that.
"I just said I wanted something with vodka in and then we must have swapped numbers before I walked off.
"At first I didn't realise he got my number as he didn't text me that night or the next day.
"I paid him back straight away even though I wasn't going to at first as I thought it was so cheeky, but then I thought he might have needed it.
"He wasn't my type really but I just thought that when you're out, people buy you drinks!
"It's not usually that expensive either as when I get a vodka coke from Viper Rooms it costs about £3, or £3.50.
"I probably paid for both our drinks so it's a nice dent out of my student loan before I start uni!"