At the beach, Nick has Charlie in his arms while standing in the sea. As he shouts "We're Boyfriends!", his shorts are wet all up the front - but then as he turns around to head back to shore, they are now practically completely dry.
When Nick enters into the sea carrying Charlie, you can see the amount of wet on Nick's shorts change from frame to frame. So there's a moment where they are nearly all wet, but the next frame they are just barely wet.