Rub it on like a jar of mayonnaise

lather each other (you and your partner) up in mayonnaise and spank each other while engaging in amazing sex

Person 1: Hey, I wanna try something new today..
Person 2: What did you have in mind??
Person 1: I wanted to try Rub it on like a jar of mayonnaise today..
Person 2: I'll get the mayonnaise!