Paddy wanted to be an accountant, so he went for an aptitude test.

Tester: If I give you two rabbits, two rabbits, and another two rabbits, 
how many rabbits have you got?
Paddy: Seven!
Tester: No, listen carefully again. If I give you two rabbits, two 
rabbits, and another two rabbits, how many rabbits have you got?
Paddy: Seven!
Tester: Let's try this another way. If I give you two bottles of beer, 
two bottles of beer, and another two bottles of beer, how many bottles of 
beer have you got?
Paddy: Six.
Tester: Good! Now, if I give you two rabbits, two rabbits, and another 
two rabbits, how many rabbits have you got? 
Paddy: Seven!
Tester: How on earth do you work out that three lots of two rabbits is 
seven?
Paddy : I've already got one rabbit at home!