A student spat saliva and rubbed it on his head.

Teacher: What stupid thing are you doing? Why are you smearing your head with saliva?

Student: Madam! I overheard my Mum last night telling my Dad in their Bedroom, that if it is hard and not entering properly, he should apply saliva on the head and it will surely enter! Because what you are teaching is not entering, I have to rub saliva on my head maybe it will eventually enter my head.