As other people have said above, "What even is X?" is a sort of odd phrasing being used for emphasis, similarly to other odd dubiously-grammatical constructions that the Internet likes.
A more typical usage of "even" in a similar role would be the sentence "What are you even doing?" which is just an intensified version of "What are you doing?". Even this reads to me as colloquial, but it doesn't sound especially marked and I can imagine hearing it on the street. "What even is X?" seems like a further evolution of it.
A more typical usage of "even" in a similar role would be the sentence "What are you even doing?" which is just an intensified version of "What are you doing?". Even this reads to me as colloquial, but it doesn't sound especially marked and I can imagine hearing it on the street. "What even is X?" seems like a further evolution of it.