Wait! Too much weight!

The other Justice Leaguers found it amusing to get Plastic Man to create large items out of his fists and then lose his balance due to the drastic uneven weight distribution.

Bat-roids

Flash: "Ah, Batman? Is that you? Either this is a new overly padded full-body armor suit you're in, or you're working out wayyyy too much, guy."

Shazam!

Shazam: "You know Batman AND Wonder Woman??? Oh Man! Sorry, I'm just totally geeking out right now, Supes!"

Something Fishy

Superman: "Maybe we can get Aquaman in here to talk to this fish and find out why it's wearing Green Lantern's uniform."
Tomar-Re: "For the last time, I...AM..NOT...A...FIIIIIIIIIISH!!!"

Cop-Out

Ray: "Really? You don't think that's a cop-out that you're going to Clark's Halloween party as Locutus of Borg? C'mon, Victor…."