Definition of plug along:
(v) :
(idiomatic, US) To cooperate or go along with a plan.
(v) :
(idiomatic, US) To pretend to cooperate or go along with a plan.
(v) :
(idiomatic) To take part in a charade, deception, or practical joke.
(v) :
(idiomatic) To participate in a joke or trick while hiding one's knowledge of its true nature.
(v) :
(idiomatic) To play a musical instrument in synchrony with a playback of a recording.
(v) :
(idiomatic, UK) To manipulate (someone).