Well, we thought we'd heard all the weird we were gonna from the casting couch.

As it turns out, though, director Guillermo Del Toro is sporting some sorta penchant for vicious pest control because it took Charlie Day getting his melancholy on about murdering some rats on-screen (for his TV show "It's Always Sunny in Philadelphia") for him to get offered a role in the 3D actioner "Pacific Rim."

Day appeared on "Late Night with Jimmy Fallon" Thursday to promote "Pacific Rim" and "Sunny" and revealed the strange, whiskered tie that binds those two projects together for him.

"I got a call from Guillermo Del Toro, the director," Day explained. "Apparently, he's a huge 'Sunny' fan. There was an episode where I was bashing rats called 'Charlie Kelly: King of the Rats,' and I was like haunted from murdering rats, and he said to himself 'That's my guy. That guy should be in my next movie because he killed the rats, he can kill the monster.'" That impression, by the way? Spot-freakin'-on.

Okay, so it's probably not an affinity for vermin destruction in particular which sealed the deal for Del Toro's interest — he'd actually had dealings with the now-FXX series before — but still, it's practically headline gold: "Del Toro casts a guy after watching him kill rats."

The big break really can happen at any time, then. Take notes, greenies!