Meeting the parents can be a little awkward, but one man was left horrified when he realised he'd slept with his girlfriend's mother during the introduction.
The anonymous man, 21, from the UK, took to Reddit to explain how he recognised her mother as the older woman he'd had a "cheap one-night-stand" with, months earlier.
Despite his shock, he decided there and then to be honest and, unsurprisingly, his girlfriend was left incredibly shocked. The pair agreed that they couldn't keep seeing each other in light of what had happened.
Other Reddit users praised him for his honesty, with several admitting they would have kept the night of passion a secret.
The British man took to the sub-forum, Dear Reddit, Today I F***** up to share his disastrous encounter.
He revealed that he lived in a "pretty big" town with "three decent clubs", and often bumped into the same strangers every now and then.
He went on: "A week later, I bump into her again and we talk for longer. Decide to grab a couple drinks and I end up going back to her house to spend the night."
He explained: "I noticed she was a lot older (maybe around 40) than anyone else I've slept with before, and I'm 21, so pretty much double my age - but she looked good so I figured I'd learn a thing or two."
Shortly after the encounter, he moved on and began dating another girl, 19, from Tinder.
He explained: "We hit it off and after a few really good dates she invites me back to her place (I live a 20 minute drive away)."
But as the couple walked down the street towards her house, he noticed it was the same home where he had the night of passion with the older blonde woman.
He said: "My heart sank when I watched this lovely girl turn to face me, say 'This is me!' while gesturing to the same door that I went through for a cheap one night stand."
Suddenly seeing the resemblance between daughter and mother, he felt he had to reveal all to the "lovely" girl.
He admitted: "She was shocked. Very shocked when she realised that I wasn't joking when I got her mum's name right."
He went on to tell how her reaction had made him like her even more, saying: "I knew she was level-headed from our first few dates, so thankfully she actually understood and didn't attack me for it."
He added: "We do agree we can't keep seeing each other (duh) but I really did like her, which can be rare for me, so it f***** sucks."
Other users were stunned by the revelation, with many taking to Reddit to praise the man for his honesty - and suggest they wouldn't have done the same.
One wrote: "Props man for telling the truth. You're a gem and any girl would be lucky to have you. Sorry about your rotten luck though."
Another commented: "I wouldn't have said a thing. Life goals!"
"Shouldn't have said nothing until years from now. Would've been a great joke if you'd ended up getting married with her. We'll never know now."