Well...
"Come one, come all, come see the chimp in a maze!" ...or something along those lines.
"It seems the little Saiyan has a strategy. He's going to move at the last second so the blade will cut me instead. DO YOU THINK I'M FOOLISH ENOUGH TO FALL FOR SUCH A CHILDISH TRICK?!"
..Well, I found that hilarious, because of the way Frieza looked when he said it.
"He's down there. I'm cooking up a Saiyan stew, and as a spice I wouldn't mind adding a Namek to it."
It's been sometime since I've watched the Namek saga all the way through, so I really don't know what line in particular you're talking about. Frieza said loads of things I laughed at, though they may not have been funny to you.