I may have to post repeatedly as I recall other scenes that made me laugh, but two come to mind immediately:
In Strange Visitor when the 3 Kents are looking for Clark's spaceship, Martha says, "Maybe we shouldn't have told you about being adopted." And Clark replies, "That would've been hard after I started bench pressing cars."
The other is in the episode where Martha is talking about Jung and Freud, and Jonathan looks at Clark and says, "Adult Education. It's a beautiful thing."
Cracks me up every time.
