Jump the Shark (S04E19)

A 19-year-old boy named Adam (guest star Jake Abel) calls Sam and Dean looking for John Winchester; the boy claims to be his son. Dean and Sam meet Adam, assuming he's a demon trying to lure them into a trap. However, they find out that John was, indeed, the boy's father and Dean is infuriated when he hears Adam tell of his "normal" upbringing. (Warner Bros. UK)