To stain (skin) with indelible color.

ETYM Earlier taptoo, Dutch taptoe; tap a tap, faucet + toe to, shut (i.e., the taps, or drinking houses, shut from the soldiers).
1. A design on the skin made by tattooing.
2. A drumbeat of bugle call that signals the military to return to their quarters.
3. The practice of making a design on the skin by pricking and staining.