I believe that 'reheated pineapple' actually means those grenades that look like the fruit. And there's the term 'cooking a grenade'.
Look, someone's falling out of the sky...Something just exploded.DISSIPATING~Uwah!Ugh!Woah!DONK!What just happened?Everyone stay calm, it's just master Dante throwing around a few fireworks...Really?Stop joking with us...Do your fireworks involve cooked grenades?
Reheated pineapple. Sorry, not sure the meaning of this.