It can hard enough for normal people to remember everyone they've crossed paths with in life.
And for a famous singer and reality TV judge like Guy Sebastian who no doubt meets thousands of people, it's no surprise there may be people he doesn't recognise.
Such was the case on Sunday night's episode of The Voice when Guy told All Star contestant Sheldon Riley that they "have no history together" – except they do.
As Guy pitched against fellow Aussie coach Delta Goodrem for Sheldon to join his team, he failed to show even a glimmer of recognition.
"I guess it boils down to what you want. You guys have history together and we don't," Guy said.
Heaping praise on the singer for his talents, Guy then continued: "I want to create something that's deep with you. Something that's really meaningful. And I'm fresh – I'm coming in fresh with Sheldon."
But, awkwardly, the pair had actually met before. Sheldon auditioned for The X Factor when Guy Sebastian was one of the judges – and we have receipts!
A clip of Sheldon's audition in 2016 shows the then 17-year-old being given feedback and sharing banter with Guy after performing snippets of two songs.
WATCH: We have proof! See Sheldon Riley audition for The X Factor in 2016 and oh, look, Guy is there too! Story continues after video...
"You went from being super cheesy, kind of like a kid singer to a really sexy dude singing a really sexy love song," Guy told him.
Laughing, Sheldon responded: "Oh, stop it Guy!"
Guy eventually voted to put Sheldon through to the next round and at one point even told him: "You're like a young Bruno Mars."
In Guy's defence though, Sheldon looked very different in his younger years and went by a different last name.
It wasn't the first X Factor-turned-Voice contestant Guy failed to recall though.
Earlier in the season, familiar face Vendulka Witcha from the 2012 season of The X Factor returned to audition in front of Guy.
While she didn't seem to ring a bell either, we're hoping Guy's foggy memory will clear up soon!