A Onesie is an adult babygro which is all the rage with youngsters in England at the moment. 

I have got a Onesie I wear it all the time It covers up my blemishes It makes me feel sublime If I were to take it off Then my allure would fade Thank heaven for my Onesie It helps me make the grade. 

Trouble is, I've got an itch And it won't go away I'll have to take my Onesie off To combat the decay I've other ailments deep inside That need attending to Perhaps I'll leave my Onesie off To let The Lord get through.