The picnic was just a coverup.Once FM and GL get to the Mushroom Kingdom, they realize the truth.
All toasters do indeed toast toast.However, toast is not all that toasters toast.
They have a special kind of bread that goes in toasters. It's called toast.Hence why Fat Mario says "All toasters toast toast". Another name is sourpuss bread (hence "Bowser's Sourpuss Bread"), but most people call it toast.
Gay Luigi is smitten with the player.Hence why YOU gotta help him!