Definition of subbed:
(v) :
(US, informal) To substitute for.
(v) :
(US, informal) To work as a substitute teacher, especially in primary and secondary education.
(v) :
(British, informal, soccer) To replace (a player) with a substitute.
(v) :
(British) To perform the work of a subeditor or copy editor; to subedit.
(v) :
(slang, Internet, transitive) To subtitle (usually a film or television program).
(v) :
(slang, intransitive) To subscribe.