How do you make soda flat?

There are a couple of ways to do this if you really want to make your soda flat.

First, you could shake it up a lot before or after breaking the seal on the lid. Of course, make sure the lid is tightly screwed on or you will make a mess. Also, make sure you wait until the soda is no longer fizzing before you open it, or it will spew everywhere due to air compression and release.

Second, you could refrigerate then defrigerate; refrigerate, then defrigerate, and so on. Of, you could freeze, then unfreeze; freeze, then unfreeze, and so on. Repeatedly cooling and warming of soda will flatten it.

Third, you could just leave the lid off the bottle for some time (exposing it to air) and the soda will eventually become flat.