A murder mystery

 2 boys entered a bar.

Both of them ordered a drink for themselves. 

The ordered drink chilled with ice cubes was served.

First boy gulped the drink as soon as it was served. 

Second boy was seen slowly sipping the drink.

After some time, second boy was seen dead. His drink was poisoned. 

Drink of first boy was also poisoned. 

But nothing happened to him.

How is it possible ????

Answer

As I said earlier, both of the boys drank the drink with chilled ice cubes.

The drinks ordered by both itself was poisonous. 

But the second boy was dead whereas the first one was not !!! 

The ice cubes were having the poison. 

As the first boy gulped down his drink as soon as it was served,  the ice cubes didn't melt down so as to release the poison. 

But the second boy was sipping the drink. The time was sufficient for the ice cubes to melt down and release the poison. 

Thus, only second boy was dead not the first one  !!!!