Sorta.
Some turtles are known to practice 'cloacal breathing'- absorbing oxygen through air in the cloaca- the single opening used for excretion, urination, and reproduction. This is documented in the Fitzroy River turtle (Rheodytes leukops) and may occur in others.
HOWEVER- to be accurate...
- turtles don't have 'butts' in the sense of two large masses of muscle and tissue surrounding the anus.
- even if we call that area a 'butt', turtles do not breathe through the skin and muscle there. Mammals do not excrete through their 'butts', they do it through the anus- a different body part!