Generally, in the context of gender studies anything that results in another person to making an economic decision will be regarded as 'aggressive' and reinforcing male 'hegemony', especially if the group in question is known to make really poor decisions when confronted with that question.
For example, lets say men are known to take more risk in their investment portfolios. Investments that have high risk and hence create higher returning male portfolios would then be regarded as reinforcing male hegemony.
As part of the societal trend towards equality of the genders, there's a tendency to take the standard or model for men, say that women are now allowed that standard or model, and declare equality to have been achieved. Saying these standards "exist to reinforce male hegemony" is an exaggeration, for the most part men aren't actively trying to oppress women, they're just not succeeding in achieving true equality. From a women's perspective, it's the same result, although sensationalizing doesn't really help their cause.
As a somewhat abstract example, when women are compared to men in the workplace, they're usually seen as cautious or passive. Now, this is true, that the average female is more cautious or passive than the average male (leaving aside nature vs nurture for a second). But that bolded part is critical--most people, when making the observation that women are more passive, don't realize that they're using a male standard as a basis for judgment.
It's important to note, that the differences attributed to women are not necessarily bad ones. One could just as easily say, men are rash and compulsive. And, this would also be true, in exactly the same fashion: the average male is rash and compulsive compared to the average female. But, because of historical male hegemony, the average male is taken as the ideal or the standard. Difference from this standard, even when neutral or situationally advantageous, tends to be perceived first as a deficiency.
Here's a slightly more concrete example, which I don't know if it's true but it could be: until recently, men drove cars and women were mostly passengers (this is still true in other countries). Cars were physically designed around the average male body. When women started driving, that meant that they were allowed in the driver's seats, but those seats were still designed for men. The pedal and mirror placements were sub-optimal for their generally smaller bodies. Even though women have achieved nominal equality in the area of driving, until car makers update their design constraints, women operate cars at a disadvantage because they must conform to a standard that was designed without them and that does not fit them. On the one hand it's unfortunate, but on the other hand it's inevitable, because it's not a good business decision to design a car for people who don't drive (until they do).
But that bolded part is critical--most people, when making the observation that women are more passive, don't realize that they're using a male standard as a basis for judgment.
Thist is an important insight, but one should be careful with it. Taking it too far leads to the exact same kind of backwards thinking where (taking race instead of gender) reading books is "acting white". If one group in society (men, whites, etc.) is dominant, and society continues to function, then obviously the dominant group is doing something right, and forcing or pressuring the oppressed group into doing something wrong. In the racial case, that "something" is education. Whites oppressed blacks; whites were educated while blacks weren't. The answer is to educate blacks and stop oppressing them; it isn't to tear down education itself as an artifact of white oppression.
Back to your example, sometimes someone in a traditionally male occupation has to be assertive. It's hard to imagine a passive salesperson or a passive Prime Minister being very effective, male or female; agree or disagree with them, Margaret Thatcher and Golda Meir were not passive women by any stretch of the imagination.
(Thatcher and Meir may have certainly been bad PM's in the sense of doing bad things, depending on your political views; I don't want to argue it either way. But they were certainly effective; if one agreed with and wanted to pursue Thatcher's agenda in the UK 30 years ago, Thatcher would undoubtedly be the best candidate for PM. Likewise, one can be an extremely effective salesperson while selling useless crap no one really needs.)
Can you explain what this means, and tell us some non-bedroom "human" or "neutral" activities which really reinforce male hegemony?