Why did the moss want to play with the fungi? 
He is a  fungi  {fun guy}

When is the best time to go to the dentist?
2:30 { tooth hurty }

                                              
If grownups have knees what do kids have?
kidneys {Kid Knees}

Knock knock who's there?
Thistle
Thistle who?
Thistle {This will}  be the last joke you here from me