There are two meanings to OD when you use it in the world of rap. You might already be familiar with one of them since it is a popular slang extensively used in the streets.
OD is a term popular as the abbreviation of “overdose.” Overdose is a dangerous activity where a person takes too much drugs in one go, which could be fatal. Due to the immense involvement of drugs in rap, OD is very popular.
“Chris Farley OD’d during the height of his popularity.”
OD, in a cleaner light, is used as a shortened version of “overdoing.” When someone exaggerates or does too much, then they are overdoing it.
“You might break your back if you keep OD’ing.”