Doctor, Dick, Small
Bob saw his doctor and asked if he had ever laughed at a patient."In over 20 years I haven't because I try to remain professional."
With that Bob dropped his trousers revealing the tiniest dick the doctor had ever seen. It wasn't any bigger than a AAA battery.
The doctor burst into uncontrolable hysteria. "I'm sorry I really am, I don't know what came over me, I promise it won't happen again. Now what seems to be the problem?"
"It's swollen" said Bob.