Pretending to be someone else on the phone or putting a whoopee cushion on someone's chair are two very old types of a prank, or practical joke, played at someone else's expense.
There are many kinds of pranks in the world. If you called a friend and said you were the police, that would be a prank phone call. Some pranks can be mean and even dangerous, while others are silly. Some people prank their friends, while others prank people they dislike. Some people never outgrow the need to pull a good prank. A less common meaning of prank is to dress up in a showy or silly way.