Kid cousin called me dumb so I tried to clap back... and lost

Someone was hanging out with their young cousin, and the kid called them dumb. So they tried to hit back with a clever comeback:

Me: 'You mean a treasure of the sea~? (childish tone)'

Cousin: 'No. A cockroach bodyguard.'

Me: *speechless*

They got absolutely destroyed by a small child. The last line is just blank — there are no words left.