You speak of tea bagging when a guy lowers his testicles down into someone’s mouth.
It’s called this way because it resembles the lowering of a teabag in a glass of hot water.
The easiest way to do it is to put your index finger and thumb as a ring around his scrotum, pushing the balls down.
Encircle your teeth with your lips end take the balls into your mouth. Stimulate them carefully with your lips and tongue.
Take both balls into your mouth, since drawing them apart can be painful.
Girls who give their boyfriend a blowjob often forget the testicles. Tea bagging is a nice way to stimulate a guy’s balls. But be careful. Not all guys like it. Some love their balls to be caressed and stimulated, others hate it when you even think about it.