I can't believe I never saw this clip before. It's Crispin Glover on David Letterman in 1987 absolutely out of his mind. Debate rages to this day whether this is Crispin Glover, brilliant yet eccentric method actor, or Crispin Glover, massively drugged out of his gourd. (Hint: it's option two) It's perfect for this to happen on Letterman because Dave has always been the sort of host who, when he feels an interview isn't worth his time, cuts and runs. The feelings of his interviewees have never been a high priority (see Richard Simmons, or Paris Hilton after she got out of prison).
None of those compare to this, though: