Lapse's in concentration that usually occur in the afternoon - typically 3.30pm. These lapse's in concentration typically occur because you are hungry.
It is a very common and popular expression in New Zealand and Australia.
The Continental Cup brand (soup) has produced many ads showing the consequences of three thirtyistis
I have three thirtyitis so I am taking a break (from work)
Inflammation of the entire breast area(s) of a woman due to rough sexual activity on her breasts. Fairly common condition following instense tit fucking sessions.
Boyfriend: "Honey your tits look so good today that I am going to give you a case of tititis like you have never had before!"
Woman: "I love my tits to be fucked hard, but hate when I get tititis because of it!"