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3.
A dog that is hormonally confused and is dependent on inserting its erect canine penis into the anus of another dog or human.
Luke was sexually inactive for many years until he bought a bummerdog from his local pet store and has proceeded in engaging the animal in its anal activities.
by Tonyman October 29, 2007
 
1.
a downer, could refer to a person or a a situation
don't be such a bummerdog, laurel, it'll grow back.

you saw your mother turning tricks on the ave? man, that's a bummerdog and a half!
by mix masta malicious mischief August 10, 2003
 
2.
a mooch
that little bummerdog hit me up for change again!
by melancholy fool August 11, 2003