High or drunk. Basically just "on one"
Even the principle at our school knows we keep it reisty.
(1) someone or something that smells somewhat unpleasant, a bit gopping, rancid etc.
(2) a person who's personal hygiene leaves something to be desired.
You smell like a reisty tramp.
That fart is fucking reisty.
"Go have a shower, you reisty fuck"