Left 4 Dead 2

nightmare

modpack - https://steamcommunity.com/workshop/filedetails/?id=3140149743

ips:
edging.guru:34436 (old)
edging.guru:34461 (increased max players (NOT))

or look for the nightmare tag in the server browser

nightmare: redux

modpack - https://steamcommunity.com/sharedfiles/filedetails/?id=3517393744

ip - edging.guru:34458

or look for the nightmare tag in the server browser

vanilla-ish

server ips:
edging.guru:32823
edging.guru:32824
edging.guru:32825
edging.guru:32826
edging.guru:32827
edging.guru:32828

you could also search for sex in the server tags, in the server browser
you can open the server browser by typing openserverbrowser in the console, the clicking on the custom tab

chat commands to change map (including addon maps that you might not have):
!nominate
!rtv