Before telling people you are pregnant, you might need to "hide" until you get the all clear. For my first this was at 16 weeks, when I still had a waist (I know!) and had gained very little. For the ones after that it was a joke that I was telling people at 12 weeks, since I'd been in maternity pants since week 8 or 9. Sometimes your body just remembers and springs back into action (or inaction as the case may be with my abdominal wall).
Step 1: Avoid people
Step 2: When asked why you aren't drinking you can
a) claim a newfound abstinence
b) tell people you are super sick and not drinking (but they why did you hug them when you walked in?)
c) tell them you are on antibiotics- which is the same as telling them you are pregnant
d) tell them that you are still hungover from last night- which is often believable but people will question later when they do the math and always wonder if *that* is why little Madison isn't potty trained.
Step 3: Avoid your family. They can tell something is up, avoid them.
Step 4: Find a nice place to puke.
At work, at home, in the car, on the commuter bus, the nice garbage can outside the subway stop, a storm drain, a fancy restaurant in Vegas... I've puked in every last one. My best advice is to make it comfortable if you are at home, and to find an office bathroom that doesn't need a key or code to get in with. I speak from experience.
Step 5: Avoid your friends.
Step 6: Hide behind your kids, gift bags, giant purses etc.
Step 7: Be seen eating in public as a plausible means to explain your new paunch.
Step 8: Finally tell everyone, and act surprised and disappointed that they all guessed weeks ago!