When you and your girl are doing a 69 and as soon as you cum, you drop her on her head like a tombstone pile driver and her cum just shoots up into the air. Great for lovers.
Is the numerical representation of two loving partners engaging in oral sex with each other simultaneously. One yeets his erect penis into the other mouth, whilst the reciprocating the favour.
Jill: ooh I’m enjoying this sixtyniner
Jack: gobble this
ralph and cindy enjoyed last nights tacos twice, first for dinner and then a quick sixtynoon in the bath tub where everybody got a taste of the action.