The good-looking Essex boy was more than annoyed after he noticed his clothes, bag and phone had gone missing while he was taking a swim.
But little did Dan know he was actually being pranked and, after having no luck finding his belongings, the reality star was left standing in his Speedos!
Not that we mind at all!
Next in line to be pranked by magician Ben Hanlin for ITV2's Tricked, Dan panics when he realises his phone is missing after he left it to charge on the side.
Spotting a gym attendant, Dan asks for him to check if his phone has been handed in, before realising his bag has been stolen out of his locker too.
The gym attendant, wanting to help, offers Dan a dry pair of speedos of to put on, but feeling frustrated, Dan replies: "I don't want any speedos mate, I just want my bag."
Ben eventually gives up the goods and Dan is left puzzled when his clothes suddenly appear on the manikin standing in front of him. Laughing in amusement, Dan jokes: "He better have my watch and everything else!"
When Ben finally comes clean about tricking Dan, the reality star laughs: "You've done me!"
Yep, Ben got him good!
Dan and his swimming pool drama features in the last episode of the six-part series, along with Peter Andre.
Other celebs who have fallen victim to Ben's wicked ways are Geordie Shore's Charlotte Crosby - who found herself trapped inside a sauna, Big Reunion star Kerry Katona, boxer David Haye and Corrie actress Kym Marsh.
Catch Dan on Tricked on Tuesday 28 October at 9pm on ITV2.
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Watch Dan in a clip from Tuesday's episode here: