A Facebook conversation usually between two people on a post, where they comment back and forth, each liking every comment posted by the other person.

This alternating liking is like a ladder - a "Like Ladder".

Adj. Something that is expected to have a long lifespan by virtue of having existed for a long time, based on the lindy effect, named for the New York restaurant Lindy's, coined by Albert Goldman and popularized by Nassim Taleb.