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someone that is just a bag. It's not something that just happens over night, it's a very much a gradual process. A bag brain is someone that smokes shit loads of pot most days of the week and pretty much become dependent on it. If someone is a bag they're usually pretty chill to be with as they're calm people themselves.
'Philip has turned into such a bag brain!''

'Hey Colin, what do you say we try and get the bag to come and play football with us?'
by bag brain July 16, 2014
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