Sophie Lee snapped the 19-year-old Olympian while his back was turned, cheekily posing in the foreground as she made a duck face and pointed at his bare bottom.
But it seems as if the Olympic Bronzed medallist failed to see the funny side - and ordered her to take the picture down immediately.
However, the internet being the internet, nothing can be COMPLETELY deleted; grabs of the snap are still circulating the internet right this very second.
The two pals, after the shower picture went public, then engaged in a playful war, posting incriminating selfies of each other onto their social media feeds, but most of them have since been taken down.
"That'll teach you for taking 107 selfies on my phone!" Daley wrote on his Twitter.
The pair often play pranks on one another but are, as a matter of fact, extremely close. In fact Sophie was the very first person that Tom confided to about coming out.
On The Jonathan Ross Show, Tom said: "Just telling one person made me feel so much better, just that one person took a weight off my shoulders.
"I told Sophie my best friend first as I knew she'd be really accepting of it.
"She's been so supportive and there for me."