Not off the top of my head
Do you know what intersection the office is located at?
|CRAFT||Can't remember a freakin' thing|
|CRS||Can't remember stuff|
|IDR||I don't remember|
|IIRC||If I remember correctly|
NOTTOMH is an acronym that stands for "Not off the top of my head," which is another way to say, "I can't think of it right now." The acronym is typically used online or in text messages when the sender is stumped for an answer.
The acronym is not commonly used since it is rather long and there are shorter acronyms that could also do the job, such as IDK or DK. The phrase is typically used by older people, so if you do receive it, it is most likely from your mom, dad, grandma, or grandpa trying to be clever.