When you find a penis that is an exact match to your own. Liketwins separated at birth, but attached to a different person.
I was giving head to this guy, and it felt like i had seen his dick somewhere before . I realized it was MY dick. If i suck my doppledonger, isnt that like giving myself head?
DAH-PULL-DANG-ER (pronoun) is an interchangeable term typically used to describe an indescribable object generally that one was just using and now cannot find, furthermore and for whatever reason, the individual cannot articulate what exactly said item was only further compounding the verbal breakdown. Insert 'doppeldanger' to expedite communication despite limited information.