The expansive exploration of the anal cavity taken to an extent far beyond typical examination. In order to be considered an ass spelunking specific symptoms must be present. Extreme pain, euphoria, nausea, loose stool, and loss of bowel control are typical. In order to be an ass spelunker one must have partaken in at least 75% of the anal event and have documented the such thoroughly. Any accomplice in the even is referred to as the secondary spelunker.
Many times ass spelunking is used in reference to homosexual acts, however, ass spelunking can also refer to those of hetero origin.

Got the covid-19 vaccine

A prank played on someone who is sleeping. When you pull down your pants stick their nose in your crack and then fart. May cause nosebleeds and/or loss of consciousness.

to eat someones ass

The act of opening and expanding the anal cavity of ones partner and then proceeding, with cave diving gear (ie: Carabiner, ropes, headlamps, etc), and entering the damp ridged caves of your consenting adult. Occasionally returning to the surface for air.

The act of exploring the dark depths of male ass hole

Its Where a person jumps into another persons ass! Usually an insult to your fellow man.