Quite a funny hybrid indeed: if I pay you to take my money, and you pay me to take your money, somehow GDP would have increased. It's a measure of economic act

Quite a funny hybrid indeed: if I pay you to take my money, and you pay me to take your money, somehow GDP would have increased. It's a measure of economic activity (of which our little give-and-take game would be an example) and it is meaningful under the assumption that all that activity happens for more rational reasons than just trolling economists. Note that our little give-and-take game would be a very expensive example of such trolling, if somehow the tax-man got involved.