gay [Homosexual] /gei/ adj. infml - HOMOSEXUAL
gay /gei/ n. [C] infml
gay [Happy] /gei/ adj. dated (of a person) happy, or (of a place) bright and attractive.
OK....so, if 'gay' is used, along with >

as a comment on a wallpaper, etc, it is clearly none of these meanings but is, in fact, the modern childish derogatory colloquial that equates 'gay' [or homosexual] as sub-standard in some way, and is intended as a comment expressing displeasure.
However, what it ACTUALLY IS, is a self-declaration of the commenter's immaturity and lack of communicative vocabulary.
It is also inappropriate, and grounds for Exiling/exclusion from participating on this site.