Hijack

Humans use this word when someone/something has taken over something controlled by something else.
Basically “stolen”

My plans was hijacked!

hug-hijacker

Someone who swiftly steps in between two other people who are about to embrace, so dat HE gets da hug from one of da starry-eyed squeezers instead of da hug's intended recipient.

Being a habitual hug-hijacker may indeed feel hilarious to you personally, but to avoid distressed feelings, you should always make sure dat (1) you know both people involved fairly well, and are already on hugging terms wif dem yourself, and (2) said couple presently has enough time for said horsing around, and was not simply needing to just "share a quick lovey" before rushing off in separate directions, and (3) da occasion is merely a moderately-casual encounter --- i.e., da two cuddlebugs are not in da middle of a tragedy or other stressful situation where da hug was meant for emotional comforting, moral support, etc., and thus it is not something to be made light of.