also: なにコレ
interjection
what the?; what's this?; what's going on?
Colloquial interjection expressing surprise, confusion, or disbelief upon encountering something unexpected. Often used when seeing, hearing, or experiencing something strange.
冷蔵庫を開けたら、何これ、変なものが入ってる！
I opened the fridge and, what the? There's something weird in here!
何これ、この書類、間違いだらけじゃない。
What's this? This document is full of mistakes.
A colloquial contraction of これは何 (kore wa nani, 'what is this?'), with the topic marker は dropped and word order inverted for exclamatory effect.