Having sex with the teacher

Little johnny comes home from school on a friday afternoon and tells his mom he had sex with the teacher. Johnny's mom was very upset with him and sent him to his room with the warning his father would be home soon to discipline him. Johnny's father walks into his room and closes the door behind him. He says " Johnny, don't tell your mother this but I am VERY proud of you, you're just like your old man! First thing tomorrow morning we are going to the store so I can buy you a brand new bicycle" The following morning johnny and his father go to the store and buy a brand new bike. Johnny's father says " Go ahead son, you can ride your bike home I'll be alright walking by myself." Johnny refused to ride the bike and insisted on walking home with his father. Johnny's dad started to get upset thinking his son was ungrateful for the new bike he just bought him. He finally questioned johnny about why he didn't want to ride his bike home and he replied,

"My ass is still sore from having sex with the teacher"