Cement Shoes/Overshoes / Sleeping with the Fishes
...and yes it's a trope
When gangsters are punishing someone for crossing them, they are often shown having the victim tied up to a chair with his feet in a barrel, into which is poured quick-drying concrete. Once the concrete is dry, the victim is then dropped into a body of water, simultaneously killing the target and disposing of the body in a supposedly untraceable manner.
Alternately, the victim is left tied up at the bottom of a construction site while the basement is being poured.
Cement shoes or Chicago overcoat is a largely fictional method of execution and/or body disposal, usually associated with criminals such as the Mafia or gangs. It involves weighting down the victim, who may be dead or alive, with concrete and throwing them into the water in the hope the body will never be found. In the US, the term has become tongue-in-cheek for a threat of death by criminals. Only one real-life case has ever been authenticated.
...but it's largely overstated (movie examples given)
Despite being a theme in Hollywood movies like Lady in Cement and books like E. L. Doctorow's Billy Bathgate, whether such a cumbersome and time-consuming method of execution was practical remained in question. Cement takes many hours or even days to fully harden and, until 2016, there was never a documented case—although crime historian Thomas Reppetto said there have probably been real-life examples that have never been found.