If You Call Before Midnight Tonight

In TV or web advertising, a fake deadline or restriction to give an impression of scarcity, to fool viewers into thinking they're getting a special deal.

This trope takes the following forms:
 * "If you call before midnight tonight, we'll give you a special bonus!" Related to But Wait! There's More!, if you call now they'll throw in a few more things to sweeten the deal. But you had better be quick, this offer expires.
 * "Call in the next 5 minutes for a special bonus!" The deadline is usually a hoax; the person who takes your call probably has no idea whether or not the commercial ran in the past five minutes in your area, and will give you the "special offer" either way, so long as you ask. Note that legally, while calling "within the next 5 minutes" must in fact give you the special deal, they don't explicitly say you won't get the deal after the 5 minutes. Others may include an allegedly 'live' order counter in the style of those used on QVC and HSN, but as the commercial is pre-recorded the counter literally means nothing at all.
 * "Last names A-M may call today, all others must wait until tomorrow." Frequently appears on consecutive days.
 * "FREE BONUS! This offer expires at midnight [today's date]" in disreputable web ads. Check back each day, and you'll find the offer unchanged and the expiry date auto-incremented by one. Alternatively, changing the date on your computer manually would also work (unless the time is stored on the server somehow).
 * Shifting expiration date - for example, the Disney Movie Rewards program likes to tell customers that their points for the program may only be valid until a certain date. Then, months before that date rolls around, they'll announce that all points ever issued are still good, even if it says somewhere that they've expired.
 * Legal advertisements often warn - "Call now, the law may change!"

The extras are generally either more refills, a travel sized version of the product, or something completely unrelated that they have a warehouse full of.

This takes advantage of the principle of scarcity, wherein, if one thinks that something's not going to be available in the future, one is more likely to buy it now, even if one wouldn't have bought it in the future anyway. It also encourages spontaneous buying, by preventing the consumer to think if he really needs the product, and deciding that maybe he doesn't.

Depending on to which extent local laws force advertisers to disclose the terms of said special offers, it can be very interesting to hear the frenzied "call NOW!" pitch while small letters on the bottom of the screen inform you that, in fact, the offer is valid until December 31 of two years from now.

This trope may appear in fiction as a final incentive to get a character to finally purchase that new thingamabob.