A strange yet witty phrase from the gay community, parodying ads that scream "buy now, pay later!" "Bi now, gay later" reflects the somewhat widely-held beliefs that anyone identifying as bisexual:
(1) is not "really" queer,
(2) is not ready to "fully" come out yet,
(3) is just sitting on the proverbial fence before the supposedly inevitable choice of what they really prefer,
(4) is somehow just trying to be "chic"....

Gay visibility is very high compared to bi visibility. For example, "gay" is treated as the default queer sexuality in questions like "How can you kiss guys and still wonder if you're gay?" So it often seems as if all bisexuals "turn gay." In reality, many bisexual people initially came out as gay as well as vice versa.

In some cases, someone coming out as queer may identify as bisexual initially because they know they are attracted to the "same sex" but are not sure whether they are also attracted to the "opposite sex". If they determine that they are not, they might later come out again, this time as gay. If they determine that they are, they might later come out repeatedly, as bisexual, over and over, as their peers insist that they "pick a side." The bottom line: bisexuality is valid and sexuality is fluid.
