Dewey wanted to be an accountant, so he went and took the accountancy exam.

Examiner: If I give you two rabbits and then I give you another two rabbits, how many rabbits do you have?
Dewey: Five.

Examiner: No, listen carefully again. If I give you two rabbits and then I give you another two rabbits, how many rabbits have you got?
Dewey: Five.

Examiner: Let's try this another way. If I give you two bottles of pop and then I give you another two bottles of pop, how many bottles of pop have you got?
Dewey: Four.

Examiner: Good! Now, if I give you two rabbits and then I give you another two rabbits, how many rabbits have you got?
Dewey: Five.

Examiner: How on earth do you work out that two lots of two rabbits is five?
Dewey: I've already got one rabbit at home!