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.
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.