This Star Trek t-shirt features an illustrated poster that shows Captain Kirk and Spock in the fictional movie "The Tribble Terror!" Tribbles first appeared in the Star Trek episode titled "The Trouble With Tribbles". Tribbles are small, non-intelligent lifeforms originating from Iota Geminorum IV. Known for their prodigious reproductive rate, these round, furry creatures emitted cooing sounds while touched, which had a tranquilizing effect on the Human nervous system.