What's the best place to go shopping in the ocean?

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?

There is a place where if I stand up straight, I will still be considered sideways.

I am lying and I always lie. Tell me whether I am lying or telling the truth.

A man dies of old age on his 25 birthday. How is this possible?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

Four cars come to a four-way stop, each coming from a different direction. They can’t decide who got there first, so they all go forward at the same time. All 4 cars go, but none crash into each other. How is this possible?

2 ladies and 2 girls need to cross a river in a boat big enough for 1 LADY or 2 girls. How do they do it?

Without looking at a calendar, within a minute name, a boy's name using 5 consecutive 1st letters of 5 consecutive months

What kind of tree can you carry in your hand?