Both 5 Seconds Of Summer and All Time Low are touring the globe this summer. And while both acts are no stranger to life on the road, the guys from 5SOS say one member from ATL is notorious for making a rookie mistake when traveling.

"Jack spent a couple days out on the road with the 5 Seconds guys last year when they were touring and they're convinced that Jack might have gone poo poo on their bus," Alex from ATL told MTV News.

"That's a big no-no on tour buses, by the way," the band's drummer Rian chimed in. "You can pee pee, there's no poo poo."

While Jack insists Calum from 5SOS is to blame -- "He's responsible for everything that it wrong with that bus" -- his bandmates seem to think he's guilty of the accusation.

"I think Jack just felt the luxury of being on someone else's bus for once and not having to worry about it," Alex explained. "So I think he let loose."

But it's not just Jack letting loose on tour. When asked if he had any shade to throw at 5SOS, Jack shined a light on a subject where the sun don't.

"I'm going to be honest with you, I don't think I've ever been around four dudes and seen them naked as quick as it happened on that tour," Jack laughed. "And that's saying a lot because we are one of the most naked bands there are and as soon as I was on that bus, 10 minutes later everyone's got their clothes off, they're dancing around like it's some weird, like, little, I don't know, a nudist colony or something."

"It's a big naked poop party," Rian added.

Outside of the dumps and di--s drama, ATL has nothing but love for 5SOS and are super impressed by their growth as a band.

"You see a lot of younger bands that blow up relatively quickly and they kind of become detached and not the greatest dudes but we've known them from when they were kind of just starting to get that success and now they're huge and they're the same dudes, same nice guys," Rian said. "And then Jack poops on their bus and ruins everything."