Blind firing turtle shells

You are in the middle of an online game of Mario Kart and hit an item box. Instead of getting a useful item you are stuck with a single green turtle shell. There is no one in front of you to fire at, what do you do? You carefully watch the map and try to line up a shot with the player behind you, hold your breath and fire. Hopefully you will see the other players icon on the map start spinning and your character do a little victory pose. This is what I just did 10 minutes ago and it felt great.