hot mud

a name used for fast setting drywall joint compound. Hot mud is used to make repairs and patches or when wallboard taping and finishing times need to be faster. You can buy quick-setting compounds with approximate setting times of 5, 20, 40, 90, and 240 minutes. These products are often referred to by their minute rating, such as, “20-minute mud”.
The reason these products are called hot mud is because when they are mixed with water and harden, the material becomes very hot.

Alternate spellings and misspellings: hotmud