Fact: when you have over 30 birthday cakes, you're bound to have some leftovers. And after my BYOC (Bring Your Own Cake) birthday party to celebrate my recent 30th birthday, I found myself with over 36 types of cake. What to do to maximize the leftovers in such a situation? Luckily, I had a few ideas. Here they are, in case you ever find yourself in such a situation:

Enjoy it the morning after, straight from the fridge or freezer. It's not elegant, but it has its charms.
Birthday Cake Bread Pudding.
Leave it at the bus stop in a tupperware container with a note for someone to find it. I'd eat that if I found it at a bus stop.
Birthday Cake French Toast.
If it's cupcakes...Bake 'em in MORE cupcakes!
Chocolate Covered Cake on a Stick. Hey, they do it with cheesecake and Key Lime pie!
Use one of these tricks to bring it back to life.
Cake Crumb Cookies. I'd never heard of them til today!
If one of them was a cheesecake, make a Grilled Cheesecake.
Make trifle.
More specifically, make a "Russian Cake" or "Creole Truffle".
Share it with the public (that's what I do at my store!).
BIRTHDAY CAKE SHAKE!
Crumble it up and use it as an ice cream topping or mix-in.
Use it as a cinnamon roll filling! Like this recipe, but with cake instead of cookie dough.
Slice it into thin slivers and use it to line a pie plate. Prepare a batch of your favorite no-bake pudding or cream pie filling, and pour it into the cake-sliver "crust". Possible flavor combinations: Hummingbird cake with banana pudding filling.
Crumble it and make cake pops, adding a little extra frosting or butter if needed to make the filling hold together; coat with melted chocolate or candy coating as in this recipe.
Similar, but with booze: make rum balls.
Make Birthday Cake Soup.
Make "chocolate salami". No, I am not kidding. And no, I didn't invent it, but I'm glad it exists.
Use two thin slices as the bookends to an especially decadent ice cream sandwich.
Make a cake-plate sampler and share it with your next-door neighbors. Extra points if you give it to a neighbor you've never met before.
Make cake croutons, the perfect topping for candy salad!
Use it (cake only, no frosting) to line a tart or pie pan before baking (it will keep things from sticking).
Make a charlotte, using sliced birthday cake in place of bread or ladyfingers.
Crumble up an entire slice and bake into a batch of brownies. You'll be rewarded with crunchy bits and swirls of buttercreamy frosting.
Top it with jam and eat instead of toast for breakfast. Healthy!
Birthday cake cereal. Cut it into half-inch cubes and put in a bowl. Pour milk over it and eat with a spoon. Better than granola!
Cube it and entomb it in an awful but awesome-looking jell-o mold.
Deep-fry it. On a stick, if desired.