Figurative: "If you want to discuss this topic with me, you will need to wait your turn, as there are any number of others who wish to do so who got here before you did."
Comes from a line control mechanism that is found today with decreasing frequency, where one is requested to take a numbered ticket from a strategically placed dispenser and accordingly wait for that number to be called.
Your computer just blew up? Take a number, I've been getting calls on that all day.
One of the largest and most popular internet service providers, simply owing to the advertising barrage they've committed to since the September That Never Ended started.
They have a reputation for having bad customer service, even worse users, and downright horrible connection lag on their dialup, complete with a proprietary bloatiferous client. Those that want off have a hard time getting off due to the fact that they won't forward your email.
From a commercial: "A friend of mine told me I should try America Online. 'Why?' I asked. 'I already have a computer!'"