itching to show off one's skill
Rare literary noun describing the urge to display one's ability. Often appears in the set phrase 技癢に堪えない (cannot resist showing off).
Unable to resist showing off his skill, he ended up starting to play the piano.
Variant kanji form, even rarer than 技癢.
The exact derivation is uncertain. The spelling 技癢 combines 技 (skill) and 癢 (itch), literally 'skill-itch', suggesting an itch to use one's skill.