Final answer:
The situation described is an example of discrimination, specifically a form called heterosexism, supported by prevailing homophobia. It reflects historical and ongoing struggles against discriminatory practices, akin to those confronted during the civil rights movement.
Step-by-step explanation:
The "help wanted" sign followed by "no gays need apply" is an example of discrimination based on sexual orientation. This is a form of heterosexism, akin to racism and sexism, where prejudice based on someone's sexual orientation creates systematic disadvantages. It is similarly propelled by homophobia, an irrational aversion to homosexuals. Much like the civil rights activists who fought against various forms of discrimination, individuals and groups have taken steps to combat such injustices. For instance, Angela Douglas and the Los Angeles Gay Liberation Front picketed in 1969 against a bar that posted a discriminatory sign, similar to how Rosa Parks protested against bus segregation.
These discriminatory practices can lead to a self-fulfilling prophecy, where negative stereotypes affect the treatment of individuals, thereby perpetuating a cycle of prejudice. Initiatives like the repeal of "don't ask, don't tell" by President Obama and the proposed Employee Non-Discrimination Act are modern efforts to curb such discrimination in institutions.