have lead in one’s pencil

have lead in (one's) pencil

vulgar slang To be able to have an erection. You'll have lead in your pencil, guaranteed, after following this six-step program. I was so drunk that I didn't have lead in my pencil, if you know what I mean.
See also: have, lead, pencil
Farlex Dictionary of Idioms.

have lead in one’s pencil

1. tv. to be vigorous and active. (Widely known phrase. Not taboo.) Your problem, Tom, is that you should have more lead in your pencil. You just don’t have the stamina.
2. tv. to have an erection of the penis. (Usually objectionable.) Due to his drinking habits, he never has any lead in his pencil.
See also: have, lead, pencil
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • have lead in (one's) pencil
  • pencil
  • put lead in (one's) pencil
  • put lead in one's pencil
  • put lead in your pencil
  • lead in (one's) pencil
  • lead in your pencil
  • make a mountain
  • in pencil