PCSA, Vampire Taps and All-In-1...
Damn you, I'm still drinking to forget them...
Shouted across a room - "Log in to All-In-1, I just sent you a message!"
Thicknet cables with their 15-way D connectors used to confuse users, who would plug them into the joystick port on their sound cards and wonder why they couldn't connect. (Younger readers - this is much like plugging your RJ45 network drop cable into an ISDN card),
Thicknet was positively skinny compared to the inter-floor hydra cable I encountered on one site. BICC ISOLAN hubs serving two floors, delivering RJ45 Cat 3. Yes, you read that right, Category 3. I can't remember how many U's they took up in the cabs, but "many" springs to mind.
For extra giggles, the ISOLAN network cards in the PC's would release their magic smoke if anyone ever attempted to install Windows 95. Log in, and your machine would be impersonating Robert the Robot from Fireball XL5 within moments.