lead in (one's) pencil

lead in (one's) pencil

An increase, enhancement, or restoration of one's sexual ability or vigor. Following this six-step program will put lead in your pencil, guaranteed. The only real way to put lead in your pencil is to eat well, exercise regularly, and have self-confidence.
See also: lead, pencil

lead in your pencil

vigour or energy, especially sexual energy in a man. informal
1972 Dan Lees Zodiac The couscous is supposed to put lead in your pencil but with Daria I needed neither a talking point nor an aphrodisiac.
See also: lead, pencil