Why did the gay man want to work at the electric company? He knew a lot about GRIDS.
Why do you think people will be upset about this joke about gay men?
Because you can't say that about a gay person, it's just mean - capiscious.
Being LBGT is hard since so many in society don't support you, so joking about it can be hurtful. Making light about gay people having aids can be hurtful, just like you would be hurt if people made a joke about something that caused you pain.