Simplify the following text for a Grade 11 native English-speaking person.
Original: Commonly , this sex act involves the man placing his penis in the woman 's cleavage and thrusting between her breasts , while the breasts are squeezed around the penis for additional stimulation .
Simplified: Commonly , this sex act involves the man placing his penis between the woman 's breasts and thrusting , while the breasts are squeezed around the penis for additional stimulation .