comes from the slang term used to describe smoking cocaine (free-basing). Since cocaine is highly addictive, people generally always have it on their mind and will do anything to get it. Henceforth, this term can be applied to anyone who exhibits these characteristics regardless of the drug they use.
Ex: Derek has pot. He smoked Phil out an hour ago, but Phil wants to smoke again. All Phil can think of is smoking again, and he keeps asking Derek if he wants to as well. Derek does not want to yet, and eventually replies, "I'm tired of your basser attitude!"