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).
I have not yet read any of Cooper's stuff, though once I get my new library shelving up, conspiracy stuff is probably going to be what I start hunting at 2nd & Charles and Half Price Books.
I actually got into conspiracies the other way round, looking at stuff the military did in WWII and the early 1950s. Like the antigravity flying bells at Wright-Patterson and the Lenticular Bomber prototypes.
That is a fascinating topic