Talking and rambling on and on in a social setting with friends about random and ridiculous subjects while drunk or intoxicated in some way. A drunk version of "shooting the shit".
After they left the night club, they went to a nearby coffee shop and were shitshatting all night long until closing.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi