Porticullis 

A term used in reference to a male who, as a way of showing his affection to a female, protects her very zealously from the advances, real or imagined, of other males, despite the fact that she has no interest in him or even a boyfriend.

This leads to the following other slang terms:
The castle--the girl in question
The king--the girl's boyfriend (as in "the king is in the castle"
To storm the castle--to hit on the girl, not seriously but just to antagonize the porticullis
Also: boiling oil, trebuchet, battering ram, protracted seige, etc. can be used allegorically to describe specific situations that arise in this setup.

When Jamie but his arm across Yling's shoulder, just as a friend, Clint freaked out and yelled at him (because Clint wants him some Yling) even though Yling's boyfriend Adam didn't care.
In this instance (and many others) Clint was being a porticullis.

Porticullis by Jmtas May 21, 2006

Portcullis

Portcullis is the term given to strong, grated doors found in fortresses and castles around the world. These doors are usually made up of iron or other hard-to-break material such as stone.

By the way, where did you hear this term? No, seriously, not even I remember where I first heard it.
Well if there's one thing I think is worth noting is that your vocabulary is definitely expansive (If you found this on your own, that is.)

The portcullis ahead blocks our path, there's no way around it unless we manage convincing those guys to get it out of the way for us.

Portcullis by szjfdolyhhmntakietutuzqfezwqoh April 27, 2017