Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

Two guards were guarding the camp.Guard-1 was looking towards the south to make sure no threat is coming from the road.Guard-2 was looking at the north to make sure no threat is coming from the top. Suddenly Guard-1 ask the Guard-2 why he is smiling?How Guard-1 knows that Guard-2 is smiling?

What does the below rebus riddle means?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

What can go through glass without breaking it?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

There is a barrel with no lid and some wine in it. 'This barrel of wine is more than half full,' said Curly. 'No it's not,' says Mo. 'It's less than half full.' Without any measuring implements and without removing any wine from the barrel, how can they easily determine who is correct?

Can you replace the X (both small and big x) with the numbers between 1 to 19 such that all the rows of 3 numbers between X (big x) sum to 23?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?