I think it's fairly obvious that I love The Flash and the only thing possibly cooler than him is Michael Rosenbaum as The Flash. And only very slightly less cool than that is Michael Rosenbaum as Lex Luthor in Smallville.
Put 'em all together and you get one heck of a hilarious Justice League episode.
Sure, it's a little light on plot and doesn't progress the overarching story much, but hey, it's a really fun episode.
Synopsis: When the JLU attempts to search Flash's brain for Grodd's whereabouts at the exact same time Luthor is hacking into Grodd's brain for information on Brainiac, Flash and Luthor switch bodies and hilarity ensues. Though the hilarity is mostly on behalf of Flash in Lex's body, trying to lead the villains.
The only thing that could've made this episode better would have been if the plots were more parallel with no one realizing that Lex is in Flash as well as the other way around. I would have loved to see Lex raise havoc in more than just the physical way in Flash's body. But Flash in Lex was just plain brilliant.
Keep 'em coming.
"You going to wash your hands?"
"No. ...Cause I'm evil..."