Summer, booze, some crazy Finnish stuff, and um… yeah..
Ajaa means nowadays to drive, for example, a vehicle. It has the same idea of rush and motion if you chase or hunt something, so ajaa is also = to chase.
Therefore, “ajaja” is “a driver”, but “asianajaja” is an advocate (not to be confused with “aasinajaja”, which is a donkey driver. ) Also in English “drive” has abstract meanings in some idioms, such as “it drives me crazy”, “se ajaa minut hulluksi”.
But if you think, you “drive your brain”, that’s why “ajatella” means “to think”.