a penis that is so large, it can fill up a backpack. Used as a insult to people who dont know what it is , or a compiment* , to tell someone they have a big package .

* - both people involved have to know what a dick backpack is , or it dosent quite work .
insult
- guy calls girl a bitch -
girl : youre a dick backpack !

compliment
- 2 mates have sex -
mate 1 ( boy ) : that sex was great !
mate 2 ( girl ) : i know ; you totally have a dick backpack .
by hgtsydkilouuyggh March 6, 2011
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