tweak 
(twēk)
(twēk)v. tweaked, tweak·ing, tweaks
v.tr.
1. To pinch, pluck, or twist sharply: tweaked her sister's ear.
2. To adjust; fine-tune: tweaked her computer setup.
3. To make fun of; tease.
v.intr.
Slang
Slang
1. To behave in an agitated or compulsive manner, especially when under the influence of a stimulant drug.
2. To be under the influence of a stimulant drug, especially methamphetamine.
n.
1. A sharp, twisting pinch.
2. A small adjustment: made a few tweaks to the sound system.
3. A teasing remark or action; a joke.
[Probably variant of dialectal twick, from Middle English twikken, from Old English twiccian.]
tweaker n.
tweaky adj.