GS(Ep1 and a few others):When Kira keeps saying to Cagalli, "A girl?" I laugh for some reason everytime he says that.
GSD(Ep15):When Auel jumped those soldiers picking on Stellar, then ran away like little school girls after Auel showed up with his gun to the guys neck and whatever. FEAR AUEL!
GSD(Ep35):When Yzak yells at the soldiers for their stupidity and as they are walking away Dearka says "Your head is going to explode anyday now.", and Yzak is like "Shut up!".
And the other funny moment already stolen by Terra.