Sian Ferguson writes at News24:
Where exactly do we see sexism against men? Anything that perpetuates gender stereotyping could be considered sexist. I absolutely detest woman saying things along the lines of ‘men are all the same’ and ‘men are all after one thing’, because it’s sexist. The idea that men are driven entirely by sex (and that women, by contrast, have very little desire for sex) stems from patriarchal expectations of male sexuality. Not only can the acceptance of such stereotypes damage relationships (imagine trying to be in a relationship with someone who constantly second-guesses your intentions because of an untrue stereotype they were brainwashed into believing?), it damages the male psyche and perpetuates patriarchal ideas. As patriarchy advocates the strict adherence to certain gender roles, it asserts that men should behave in a certain way to be considered ‘men’. This is sexism against men. While patriarchy values men over women on a general level, it also values certain men (more ‘masculine’, athletic, straight, etc.) over certain other men (more ‘feminine’, homosexual or transsexual, etc.).