A Cave!

Punch isn't clear on what Sunder is nopeing about, but she's not about to let a nope go un-punched. She slides up next to Sunder, switching to her silvery gloves, and tries to punch in-synch with Sunder's punch, at the same thing (Whatever it is.) Since Punch's gloves can punch metaphysical things, but she has to know what to punch.

She isn't sure if 'the same thing sunder is punching' will work, but it's worth a try.