expression
what on earth is this?; what the heck is this?
Colloquial, informal exclamation expressing surprise or bewilderment at something unexpected. Often used by men, but not exclusively. Similar to なんだこれは but more casual and emphatic.
See also: 何だこれは (なんだこれは)
なんだこりゃ！こんなの見たことない。
What on earth is this?! I've never seen anything like it.
机の上に変なものが置いてあって、「なんだこりゃ」と思った。
There was something weird on the desk, and I thought, 'What the heck is this?'