Low Sex Drive

An extremely old man visits his doctor and tells him, "I need my sex drive lowered." The doctor, incredulous, says, "What?? You want your sex drive lowered?" To which the old man replies, "It's all in my head;  I need it LOWERED!"

Can't do

"What's wrong, sonny?" asked the old timer sympathetically, coming over to the little kid who was sitting on the curb, crying his heart out. "I'm crying 'cause I can't do what the big boys do!" So the old man sat down and wept too.

Infrequently

Bernie and Jane are an elderly couple who have decided to get married late in life. While they have not yet been intimate, Bernie thinks it would be a good idea to know how Jane feels about this. He asks her about her desires regarding frequency of sexual intimacy. Jane replies that she likes sex infrequently. Bernie, being ever the optimist says, "Is that one word or two?"