Might be an oldie but first time I heard it
A middle aged society type goes into see her plastic surgeon about a facelift to wipe away a few years... A little anxious about going under the knife the doctor proceeds to tell her of a revolutionary 5 minute procedure:
"We attach this small knob to the back of your head and each turn of the knob will tighten the skin on your face" he explains
Excited she comes back the following day to have it attached, all goes well and 5 minutes later she is ready to leave
"Comeback for a check-up in a few weeks" instructs the doctor
Anyway 2 weeks passes and she is back for her checkup
"How is it all going?" enquires the doctor
"Great, Great but I have a two problems, my face is as taut as when I was 16 years old but, the first problem is no matter how many times I tighten the knob I cant seem to get rid of these bags under my eyes"
The doctor peers closer and answers "Ohh I am afraid those bags are your breasts"
"Well sh*t that explains the goatee then"