"And then they have sex." From the X-Files fandom
"In fact, Mulder and Scully are constantly being shot, stabbed, or otherwise critically injured, even beyond what we saw in the show. Again, this results in time spent being cared for by the other, ATTHS."

( from the "Thirty-Five Things I've Learned From X-Files Fanfiction" post on the lj community for X-Files )
by J Cook June 25, 2008
Means: AND THEN THEY HAD SEX. It is used by the X-files fandom. When someone writes "atths", he wants to say that Mulder and Scully had sex, which is very rare occurrence
Gillian Anderson on Twitter: "ATTHS (And then they had sex), twice."
by Voodoo Child. March 11, 2018
A dumb black whore who likes their moms cooch and killed their brother. Also is dating miranda cooper and gives her sloppy toppy. Has thick nubs and knows how to use them. Also probably a hooker. Stalks miranda coopers nubbies and sucks the nubs when miranda is sleeping.
Omg what an Atthew. Theyre so annoying