One of the three principal components of the dominant culture of anal penetration among gay men, effeminacy manifests as a constellation of behaviors and attitudes, including passivity and timidity, and a combination of spoken and body language which parodies stereotypically feminine behavior in a highly dysphoric and maladaptive way.
Effeminacy is supported by a gender feminist ideology which considers gay men "intergendered" and which is deeply distrustful of masculinity.
Within that ideology, masculinity -- seen as aggressive, violent, and oppressive of women and others -- is viewed as the root of all evil, and any movement of men away from masculinity is deemed beneficial.
Thus the dominant ideology encourages men to be penetrated anally as part of the process of shedding their masculinity. Effeminacy then is both a consequence and a cause of anal penetration, a relationship made explicit by such terms as "pussy boy," "bottom bitch," and "asscunt," while the culture of promiscuity links with the culture of effeminacy in terms such as "slut," "whore," and "pig."
Outside of anally receptive sex, the ultimate expression of effeminacy in the subculture is "drag," which has high status. Men who won't participate in drag or in effeminizing language such as the use of the words "she," "her," "miss," and "bitch" to refer to other gay men are labeled "drag phobic" and, of course, masculinist.
Effeminacy should not be confused with femininity, nor with such traditional feminine attributes as nurturance or conciliation.
Effeminate gay men are not nurturing, nor is their behavior conciliatory.
It's self-hating, and, in its parodic treatment of women, extremely misogynist.
Nor is there any reason to believe that effeminacy is ever an expression of an individual's core personality.
Rather, effeminate behavior among gay men is a cultural overlay -- that is, the imposition upon the individual of a set of cultural expectations to which he thinks he must conform, which in this case, is the cultural expectation that men who have sex with men are in some way women.
They are not.
Men who have sex with men are men.
For further discussion of this point, see our Man2Man Alliance policy paper Are Men Who Have Sex with Men Intergendered?
See also intergendered, masculinity, natural masculinity.