The unknown man who left the note has been praised for his honesty after he discovered the woman was actually in a relationship after they spent the night together.
But it’s not only his honesty that has got people talking – it was also the way in which he made sure the boyfriend would find out.
The man apparently decided to write a note and tape it underneath the toilet seat, where the girlfriend would be unlikely to see it before her boyfriend did.
The handwritten note read: “This chick just told me she has a boyfriend the morning after.
“Sorry to tell you like this, but I’d want to know if I was you. Sorry, bro.”
A man purporting to be the boyfriend originally posted a picture of the note on Twitter, with the caption: “My girl cheated on me while I was out of town and the guy left me this note under the toilet seat.”
The now-deleted post has been re-posted on TikTok where it has gone viral.
One person commented: “Under the toilet seat real smart.”
Another person was inspired to cause chaos, writing: ‘I’m going to do this at my mates house and watch the fireworks.”
Someone else called the man a “real one” for his honesty, writing: “He’s a real one for telling him like that.”