1. Where is the little boys' room?

2. Where is the little girls' room?
[Is the person looking for the restroom for little boys/girls or for all male/female persons?]

3 answers

male and female restrooms. The age of the person doesn't matter. It's a "cute" way to ask, "Where is the toilet?" It's thought to be "nicer" than to say, "I need to use a toilet. Where is it?"
I haven't heard anyone use the term "little girls room" or "little boys room."

It's best to ask, "Where is the rest room?" or "Where are the toilets?"
I've heard adults use the terms "little girls room" and "little boys room." I find it silly -- demeaning, actually. The terms are appropriate for children's rest rooms, such as in elementary schools, but they are not appropriate for teenagers or adults.