ちくちく

Adverb

 * 1) with a prick
 * 2) with a tingle, itch, prickle
 * 3) with a sting
 * 4) with pangs of regret

Verb

 * 1) prick
 * 2) tingle, itch, prickle
 * 3) sting
 * 4) hurt one's conscience