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
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!"