A penis
An erect penis
Basically when your penis is hard and erect it's head will be purple, hence 'purple headed'
The 'yogurt slinger' comes into play when the penis gets so sexually
stimulated it spurts out a yogurt like substance, aka
ejaculation
The man rubbed his cock for so long it slung its yogurt from its
purple headThen his roommate walked in
His roommate began sucking his cock, making him cum again
He began to softly moan
His roommate continued sucking
Soon the roommate started undressing themselves
The two got out some lube and they continued
pleasuring the man's purple headed
yogurt slinger by shoving it hard and fast deep into the man's roommates ass
Both vocalized their pleasure by moaning
'No homo', ofc :)