A higgy back is quite literally the same as a piggy back, but has a bit of a twist. Instead of the original piggyback you will get a dick in your ass.

A person who doesn't realize they are transgender yet, or is in denial; an undeveloped transgender person. When they realize, it's referred to as the "egg cracking."

A 'Higgyback' is a turn on the word 'Piggyback' meaning being carried around on someone else's back.
Hails from the region of Co.Armagh Northern Ireland. Pure slang.
Normally a side-effect of alcoholism.