Does the gecko chirp

Geckos do indeed chirp or squeak as many of them have vocal cords. However, other species in the order Squamata (scaled reptiles: lizards and snakes) do not possess them. Geckos will vocalize for many of the same reasons as other living things: mating and scaring off predators. Just today a Western Banded Gecko "yelled" at me as I sought to remove her from my classroom.

Example:
http://commons.wikimedia.org/wiki/File:Mating_call_of_a_male_Tokay_gecko_%28Gekko_gecko%29.ogg