Well I think my favourite is on the Steve Martin ep of TMS, when the All Food Glee Club are on. One of the vegetables says "Tomato you're slow", and the tomato replies "I'll Ketch-up" - It's a good joke anyway, and then there is the added touch that one does just wonder if there was a little in-joke going on there.
Another great favourite of mine, occurs in The Secret Life Of Toys. In the episode 'All Washed Up', when Ditz's arms get stuck in the air. He ends up playing a tree, and when his arms get unstuck says "I wonder how trees do it, with their arms up in the air all day?", Meanwhile Raisin says to him "Ditz, I can't believe what a great tree you make, I mean my arms would be killing me by now". -The funny bit is that these lines are really being spoken by two experienced puppeteers.
Another great favourite of mine, occurs in The Secret Life Of Toys. In the episode 'All Washed Up', when Ditz's arms get stuck in the air. He ends up playing a tree, and when his arms get unstuck says "I wonder how trees do it, with their arms up in the air all day?", Meanwhile Raisin says to him "Ditz, I can't believe what a great tree you make, I mean my arms would be killing me by now". -The funny bit is that these lines are really being spoken by two experienced puppeteers.