If you're simply trying to clarify American drug-slang, Google would probably be a quicker answer than our boards. Tweaking, among a myriad of uses of the word, implies somebody who has either used too much Methamphetamine in one sitting and is in one of the varying stages of psychosis or a user of Methamphetamine who has gone for too long without sleeping. It implies a breakdown of their executive function and their ability to reason.
I've never been a true stimulant addict, so I'm not going to make a ton of commentary on the issue, but I know that your functioning will begin to break down rapidly if you don't sleep a little bit each day. Even 3 hours is substantially better than nothing so long as it is actual sleep. A good rule when using stimulants is to not go on multi-day binges. Many of us are addicts and we're all succeptible to compulsive patterns of use, so sometimes, it can be helpful to have a sedative handy for that period of time when you're not high anymore but can't go to sleep.
Instead of using more Amphetamines, you can sort of abort the trip and with a little luck, that can turn into a full-night's sleep.
