This isn't the first time I hear this peculiar ending "-shi" added to words. It usually appears at the end of sentences. From the looks of it, the ending is supposed to make the speaker sound lighthearted, friendly, humorous. As an example, in Selector Infected/Spread WIXOSS Eldora and Chiyori both talk and behave peculiarly, using this ending.
What is the actual purpose of it?