Well, to be precise, certain types of almonds. Actually, the reason those species of almonds taste/smell like cyanide is actually because they contain higher than normal amounts of cyanide, so really, it's cyanide that tastes like cyanide.

This comment said:

I think it's a reference to cyanide smelling like almonds. In particular I remember a Jodi Foster movie The little Girl who lives down the Lane where Jodi poisons a rapist. He says, "It tastes like almonds." as he drinks the tea. Jodi Foster says, "It's the almond extract." knowing it's the cyanide.

So the punchline is setup to be something about poison but gets subverted by the hand grenade.