The Brief: By hyperbolically referring to execution, the slang term "gets the wall" is a way to say that someone should be punished for their crimes or bad behavior.

DEEP DIVE
According to a 2018 Urban Dictionary entry, “get the wall” means “to deserve to die or be destroyed, referencing when regimes would place enemies against a wall to execute them by firing squad.”
The phrase can be used more seriously in regards to people who are extremely harmful, or it can be used hyperbolically to refer to people who do annoying things. It’s commonly used in Communist, Socialist, and Anarchist online communities, and has been adopted more widely as well.
People who wear shoes inside get the wall
— Amelia® (@RealiaAmelia) September 10, 2020
Gm daily reminder that TERFs get the wall! pic.twitter.com/xGgRsuKKkZ
— Pagliacci’s doctor (@RegressiveElf) September 10, 2020
Peopl who talk about "getting the wall" definitely get the wall.
— Zoomer Nation (@Sarma_Aalia) September 9, 2020
Incels get the wall. pic.twitter.com/aKgm6IwQl0
— brain genius (@Millerheighife) September 10, 2020
anyone against free healthcare gets the wall. no questions asked. https://t.co/ZZf3Hhs0kH
— wheres my glock (@lowell_exe) September 9, 2020