there is no sexism against men, because men are not oppressed. there is objectification, absolutely, and men are affected by the principles of sexism (if you're girly you're a lesser men, because society equates anything to do with women as bad) and the dictionary definition of sexism goes both ways, but the real world doesn't abide by the rules of the dictionaries.
sexism, racism, homophobia, cisssexism, etc is all based on oppression. the privileged class, whether willingly or by history, diminishing already oppressed classes and perpetuates the behavior passed on from generation to generation.
yes, some women talk about men's bodies and judge them on how hot they are, but there isn't a culture of valuing men only for their looks, there isn't a culture of dehumanization of any men who doesn't look a certain way, there isn't a culture of fear and humiliation on men, men haven't only gotten the right to vote recently (in historical terms), men aren't denied rights on what to do with their bodies (abortions, etc), men earn more in any job by simple virtue of being a man, men don't have the amount of advertisements aimed at them saying how much they should change about themselves to be acceptable that women do.
now, men can 100% be a victim of discrimination and it might hurt on a personal level, there's no denying that, but there's also no denying that what men go through is not nearly as bad as what women (and people of color, and queer people, etc) experience. there is no comparison. there is a
recent study that shows how discrimination affects men and women, and for men, because our society is men-oriented, the discrimination is felt a minor annoyance, since whatever criticism is aimed more at men in general, as in the culture of masculinity, not one specific person, while for women, because our society has put them down so much and made it so personal, the effects are long-lasting and psychologically damaging.
we live in a systematic institution that deliberately makes it harder for women to have rights, and that's why it's worse to make sexual comments about women than men. it's like you're kicking someone who's already down.