OM

A simple way of exclaiming, "Oh man!" or "Oh man..."; may indicate surprise or worry.

OM stands for "old man," which may refer to someone's father, husband, or father, or just an old male. You will most likely see it in texts, emails, and online.

"Old man" is a common nickname for a person's dad that is a playful jab at the old age of the father. It may also be applied to a husband or boyfriend to make fun of their age and secured relationship status, as well. Or... it may also just describe a man who is, you know, old.