LWYMMD is an acronym for the song Look What You Made Me Do, Taylor Swift's 2017hit.
"Oh, it's that song LWYMMD that other Urban Dictionary entry writers decided to insert their own unnecessary criticisms of in their definition paragraphs instead of being mature and neutral"
The saying or advice means to live in the neighborhood where you want to hang out. If you live where it is less expensive and not your ideal spot, you will shop, get coffee, take walks, where you live more so than where you really want to live or get coffee, buy groceries, etc. Even if the spot is smaller and not as comfortable as you would normally like, you gain more with the neighborhood than with the house.
"I want to live in Hollywood, but the rent is cheaper in the Valley." "LWYWTH, grl!"
a christmas tradition carried out through centuries in south wales where they stick a horse's skull to the end of a pole. they then decorate the skull, put a person behind it, cover both with a sheet, and name it mari lwyd. mari lwyd and a group of people called its "caretakers" then go house-to-house singing a song about wanting to come into their home. the owners of the house are then expected to sing back with excuses on why they don't want the monstrosity entering their home. this continues until mari lwyd gives up or the home owner allows them inside. if mari lwyd is allowed inside, it and its caretakers raid your pantry and drink all your beer.
tldr: a weird horse skull on a stick that you rap battle.