Negetive Calorie is a myth?

Looks like that . I got to know that apple is a negetive calorie fruit and then some where some one wrote a mango is negetive calorie! mango? common people mango ha ha mango and negetive calorie glad they did not say sugarcane! and then came the shock a website said Grape fruit is negetive calorie food. These people have lost their nuts and bolts.
I looked at it again, there can not be such a thing as negetive calorie. It appears to be an urban superstition (pEtE guggugalu). There could be some that might have no calorie at all but negetive calorie is unlikely. Becasue it is unlikely that we will be able to measure NO ONE CAN PROVE ME WRONG people! NO negetive calorie food ok? get it?