'There's a reason for that'
Love this movie to death, just watched it again tonight. One thing I still don't quite understand is the part where Leer is reluctant to leave with his parents, and Tripp says "The man is obviously your father, he looks just like you", and Leer says, "There's a reason for that". Tripp replies something like "oh, come on, don't give me that."
What was implied by Leer? If it was just that they were supposed to be his grandparents, what was so "bad" that Tripp couldn't believe?