Fred and Mary got married, but can't afford a honeymoon, so they go back to Fred's parent's home for their first night together. 

In the morning, Johnny, Fred's little brother, gets up and has his breakfast. 

As he is going out of the door to go to school, he asks his Mom if Fred and Mary are up yet. She replies, "No". 

Johnny asks, "Do you know what I think?" His mom replies, "I don't want to hear what you think! Just go to school."

Johnny comes home for lunch and asks his mom, "Are Fred and Mary up yet?" She replies, "No." Johnny says, "Do you know what I think?"

His mom replies, "Never mind what you think!  Eat your lunch and go back to school."

After school, Johnny comes home and asks again, "Are Fred and Mary up yet?" His mom says "No."

He asks, "Do you know what I think?"

His Mom replies, "Ok, do tell me what you think?" 

He says: "Last night Fred came to my room for the Vaseline and I think I gave him my airplane glue."