Also, in Tubby's store, there are those two druggies who hang out. They say stuff like "We're Tubby's guards." and "Tubby's our buddy." And if you kill Tubby they'll say stuff like "Man, where we going to hang out now?" or something like that.
Also, if you just wait around them they'll go into this prolonged conversation where they describe what I think is them watching the Verti-bird crash on jet. I don't remember details but it was pretty funny.