Askōliazein

Κυρίως δὲ ἀσκωλιάζειν ἔλεγον τὸ ἐπὶ τῶν ἀσκῶν ἅλλεσθαι ἕνεκα τοῦ γελωτοποιεῖν. ἐν μέσῳ δὲ τοῦ θεάτρου ἐτίθεντο ἀσκοὺς πεφυσημένους καὶ ἀληλιμμένους, εἰς οὓς ἐναλλόμενοι ὠλίσθαινον, καθάπερ Εὔβουλος ἐν Ἀμαλθείᾳ φησί·
καὶ πρὸς γε τούτοις ἀσκὸν εἰς μέσον <  >
καταθέντες εἰσάλλεσθε καὶ καχάζετε
ἐπὶ τοῖς καταρρέουσιν ἀπὸ κελεύσματος. (Eubulus fr. 7)
(Schol. apud Aristophanem, Plut. 1129)

Properly speaking askoliasmos was what they called jumping on wineskins in order to make people laugh. They put inflated, greased up wineskins in the middle of the theatre, onto which they would jump and slip, like Eubulus mentions in his Amaltheia:
And on top of that you put a wineskin
in the middle (…) and jump on it, and you jeer
at those who fall off all at once.
(tr. David Bauwens)