Hatarakanai Futari - Vol. 9 Ch. 495 - Melon Ball

[MangaDex]

 

[Varler]

Nice! It's pretty rare that they can get their mom with a prank.

 

[Australis]

lol I would've lost it too

 

[Glomoro]

I believe part of the joke here is that melon is relatively expensive in Japan.