The crowds at ancient theatrical performances could be outright brutal, in the most literal sense of the word. Aristotle mentions the actor who played Amphiaraus in one of Carcinus' tragedies was thrown from the stage because the scene being portrayed upset the audience with its inconsistency. Aristotle uses ἐξέπεσεν, a verb that probably implies not physical ejection, but that the actor was forced to withdraw after being hissed at--Demosthenes explicitly connects the verb with συρίζω, the verb to hiss. There's an anecdote in Pollux about a certain Hermon, a comic actor who was called on the stage early, in the middle of his vocal exercises, because all the actors before him had been thrown out. Plato in the Republic compares the behavior of the crowd at the theater to its behavior at other large gatherings, including the assembly and law courts--in the Apology Socrates repeatedly has to ask the crowd at his trial not to shout out at him when he thinks he's about to say something unpopular or ridiculous. Aristophanes himself refers to the crowd hounding a fellow playwright of his, Crates, with hisses and anger. Indeed, showing approval or lack thereof at an Athenian dramatic performance was somewhat expected, as it could influence the judges--in the Ecclesiazusae Aristophanes appeals to anyone in the audience who liked the play and the judges together to judge his play well. Besides that audiences would bang on their benches (the Theater of Dionysus was not fully built from stone until the 4th Century), throw fruit, vegetables--even stones. Demosthenes accused Aeschines of surviving during his time as an actor by eating the figs, grapes, and olives thrown at him by the audiences at his performances. Roman audiences were no better. During Caesar's consulship, at the height of the triumvirs' unpopularity, the crowd threw out a gladiatorial exhibition with hissing (sibilis) and forced the poor actor Diphilus to repeat the line nostra miseria tu es magnus (by our misery are you great--an attack on Pompey) over and over. On the same occasion the crowd refused to applaud Caesar but applauded wildly when Curio entered. In the prologue to the Andria asks his audience please to hiss the play off the stage until it's finished. Roman theatrical performances could be quite nasty--before there were circus factions there were theater gangs. Tacitus mentions one of the leaders of the Pannonian mutiny under Tiberius as being the leader of one of these operae and we know of incidents when the audience began fighting each other over whether particular actors were any good