I have no idea of the origins of this word, so my understanding of it may be wrong, but where I come from its a phrase that means you're so completely tired that you're over tired or totally beat. I can only hguess its a reference to the fact that a lot of dogs seem to sleep a lot and thus appear to always be tired and in need of sleep.
I pulled a double shift last night and when I got home the neighbours were having a rowdy party with loud music and I couldn't get any decent sleep. I am already dog tired and I have another double shift tomorrow.
by PlaceHolder August 12, 2004
Really, really tired. Especially after having completely expended yourself. Dead on your feet. So tired you just can't.
After a 16 hour flight and an 8 hour work day, Sandra is so dog ass tired that she fell asleep in the middle of eating dinner.
by celebrityguesteditor June 5, 2019
After our week in Nola during Mardis Gras we were all eaten up with dog ass tired.
by MsJxn2DC February 11, 2018