Can I let a cake with homemade cream cheese frosting sit outside of the fridge overnight?

NO! Cream cheese is dairy and I think it would go bad. You wouldn't leave milk out over night so I would not leave anything dairy out.

It will probably be fine, but here is what I do:

I have done it by accident and it is fine. However, if I am serving the cake the next day and want it at room temp, I take it out early in the morning. Most of the cakes that I use cream cheese icing on I prefer to serve cold.

No I did that once and well it made me sick!

Absolutely not. When you bought the cream cheese, it was refrigerated. When you stored it at home, you refrigerated it. Someone may have done that, and it was ok. This is for a lot of people. If you let it sit out for more than 2 hours, you could end up with very sick people. You can't take a chance like that. It could end up tragically.

Ok, well I cleaned out the whole top shelf of my fridge and EVERYTHING is on one shelf and in the crispers hahahaha... and I THINK that It will all fit!!! Thank God b/c there is no way I would have time to frost it tomorrow before pick up!!! thanks!

While it may come as a surprise to all the folks who grew up after the invention of the refridgerator, it is possible for food to be edible and safe hours or even days after preparation, without refridgeration.

Not everyone died of food borne illnesses before the advent of refridgeration (or iceboxes) in the last three centuries. Nor did everyone on the planet have access to the minute quantities of cheesemaking that could be eaten in under 4 hours after it was finished being made.

Cheese is a method of preserving milk... as is yogurt. Fresh (not pasteurized) milk goes bad extremely quickly at any temperature, and both cheese and yogurt were developed as ways of keeping milk a safe food for many more days. In a fridge, cream cheese is dated 'best before' *months* down the road... which means it can probably manage to not turn into a lethal toxin in 18 hours at room temperature.