Common Sense
A cow was kept for observation.
Moral: The more you study, the more your common sense decreases !!
KG student : Its a cow!!
UG student : Perhaps this is a cow !!
PG : This may be cow or a hypopigmented buffalo!!
PHD : Dis may b a hypertrophied goat or an atrophied elephant with congenital anomalies!!
Moral: The more you study, the more your common sense decreases !! 
Teacher & Student
The maths teacher asked Little Billy “If you have £20 and I ask you for £10 as a
loan, how many pounds would you still have?”.
“Twenty” came the reply.
“How so?” enquired the teacher.
“Just because you ask me to loan you £10, it doesn’t mean I am going to”.