WHAT'S THE NUMBER FOR 911? Who do we call when we're in dire need of help? 911, of course. However some situations that callers perceived as emergencies, may not be so urgent.     Dispatcher: "911. What is your emergency?"  Male caller: "Yeah, I want to order a pizza.    "What's the Number for 911? is a collection of more than 170 stories and actual transcripts of strange, and hilarious 911 phone calls. Most of the people who made these calls needed help all right-but not 911 help. It is an easy read, with stops only for shaking your head, turning the page, and laughing out loud. It's amazing what some people have used their telephones for-Alexander Graham Bell would be shocked.     People love to laugh at the stupidity of others and this book shows stupidity at its, well, stupidest. Here are just a couple of the absurd 911 reports: Male complainant called and requested police call gas stations on all exits of I-95 to find out which ones are open. Female complainant called to request police officer come to residence to change battery in smoke detector as she couldn't reach it. Roger's Department Store called three times asking if they could close during a storm. Complainant called about neighbor keeping a pet cow in the yard.