I've seen a TV show by the BBC called "Brainsex". Among other things, they put together a team of approx 5 men and 5 women and had them race go-karts while measuring the T levels of each competitor throughout the race.
(Note: I am not sure how did they measure the T levels during the race. Is that even possible? Perhaps they stopped the race a few times and took saliva samples?)
Anyway, the results: men won, women arrived last. But the more interesting part was the variation of the T levels during the race.
The women's testosterone levels stayed pretty much constant.
The men's testosterone levels started to climb at the beginning of the race, presumably as a response to a competitive environment. In general, men's T levels grew throughout the race. There were some graphs that were shown only for a second or so, but even so I could tell that the growth was fairly dramatic - from 300 to 700 or so.
The guy whose T level grew the most (an amazing skyrocketing graph that looked like the guy had a 'roid shot in his arm) actually begun to behave in a reckless fashion, lost control of the vehicle a few times and ultimately lost the battle for the first place - he ended up the 4th.
The guy who won the 1st place had a pretty good increase of the T level but not exagerated. It was also a more constant increase.
If the information is accurate, I guess the lesson is - sometimes just to enter a competition can be a T booster.