punch-style can opener
Specifically a can opener that punches a round or V-shaped hole in a can of liquid, as opposed to a rotary can opener (缶切り).
I punch a hole in the juice can with a punch-style can opener.
Compound of 開 (kai, 'open'), 缶 (kan, 'can'), and 器 (ki, 'device'). The exact historical derivation is uncertain, but the word transparently means 'can-opening device'.