The joke was at the beginning--within the first 5 minutes--of season 5, episode 20, which first aired 18 December 1993.

The joke doesn't make any sense--to me, at least--but given that the MST3K reboot during the covid era--produced by Joel himself--was a gay woke-fest, you have to wonder. Maybe Joel knew something we didn't at the time.

Edit: It is a Mike Nelson episode. Immediately after the Epstein reference, Mike is ripping up a pair kid's underwear (briefs).