[1] The gloss is from the scholia vetera to Aristophanes, Clouds 983, where the headword infinitive occurs (web address 1). The proper meaning of kixli/zein is "to giggle", from ki/xlh "thrush", kappa 1693 (that is, to sound like a thrush); cf. also kappa 1695. As LSJ s.v. kixli/zw points out, the alternative definition construes the verb as "eating thrushes". See also under rho 55.
[2] Greek Anthology 5.245.1 (Macedonius the Consul): "you giggle...." (The addressee is feminine, but the Suda cites the verb as a masculine participle.) See another quote from this epigram, in which the poet scornfully rejects the advances of a courtesan, at pi 2058; cf. Madden (150-156).