In the episode "Ultrawoman", Clark insists that he wears briefs, but while playing strip poker we see that he also wears boxers on occasion.
Nitpick: Why did Superman use his potentially unstable heat vision to disable the low-frequency generator? Why not just use his strength to crush it, throw it into orbit, or similar? You can't throw and evil device TOO far away...
Thug: Mr Gadget! I watched you on TV when I was a kid! You were my idol!
Landry: Great, great, thank you, thank you. Take a hike.
Thug: Hey, I'm talking to the kid, here.
Landry: Mr Gadget has a death-ray that will make all your internal organs explode!
Dr. Klein: Picture in yor mind's eye a white beach... gentle surf... clear blue skies caressed by graceful clouds... the songs of chimps afire with the mating urge...
Superman: Dr. Klein?
Dr. Klein: Oh, sorry.
Dr. Klein: Look, I'm going to run every test I can, then I want you to go home and relax. Soak in a tub and do nothing.
Superman: But I'm Superman.
Dr. Klein: So? You can't play a little golf?
Dr. Klein: Often we find that true power comes to those who first agree to be powerless.
Superman: Rumors are far more dangerous than the truth, and I never hide from the truth.
Goof: Lois calls Clark "Dean" when he is trying to stop cooking the meat with his unstable heat vision.