The context is from the movie "Fear And Loathing In Las Vegas" One of the characters at the begging of the movie describes the drugs they bought for the trip to Las Vegas.
DUKE:
We had two bags of grass, seventy-
five pellets of mescaline, five
sheets of high powered blotter
acid, a salt shaker half full of
cocaine, a whole galaxy of multi-
colored uppers, downers, screamers,
laughers... Also a quart of tequila,
a quart of rum, a case of beer, a
pint of raw ether and two dozen
amyls.
Not that we needed all that for the
trip, but once you get **locked into**
a serious drug collection, the
tendency is to push it as far as
you can.
This is a definition from macmillandictionary I suspect might be the correct one here.
(lock someone/something into something) to involve someone or something in a system, plan etc in such a way that they cannot easily escape from it The currency is now locked into the European Monetary System. Their strategy is to lock subscribers into long-term contracts.
Does it mean that they got involved in a plan of collecting drugs for their trip to Las Vegas and they felt obliged and compelled to buy as many as they could?
