I readily admit I sometimes use double entendres in the hopes of increasing the chances a post will be read. However, in this instance: 1) I've always heard and called, minor adjustments to equipment, vehicle performance or athletic performance by a subtle or slight change that can have a big impact, "tweaking." 2) I've heard the phrase as a drug related behavior before, however, I've had very limited experience around "hard drug" users. If it is about beer, I'll get it...hard liquor probably, dope most likely...past that...my vocab and usage is unintentional.