Back in the '80s, Robert Downey Jr. was insane.

So insane that he, um, defecated on a seat in the trailer of one of his "Weird Science" co-stars.

Renee Props, who had a very small role in the film (to be clear: she did NOT portray Hilly as TMZ points out — she portrayed Babette Props of The Weenies), chatted with TMZ and revealed the now Oscar-nominated actor was almost fired after pulling the stunt!

Naturally, we wanted to see what the rest of the cast from the classic 1985 hit has been up to these days.

After you watch Renee recall the incident, take a look above to see how much they've changed in 29 years!