Go to a hardware store. Ask for a paint stick. Buy or steal it. Then put beer in it and do this.
Now say you find yourself somewhere (a wedding possibly, a funeral, your bar mitzvah, job interview, etc) that is not a conducive or appropriate environment to say, be slamming beers into your face using a piece of industrial equipment. You should get the fuck out of there and go somewhere else and slam beers into your face using a piece of industrial equipment. However, if this is not possible, some discretion is necessary. That is where your new friend "The Beer Belly" comes in handy.
Step 1. Get a large McDonald cup, a lid, and a straw.
Step 2. Insert and open canned beverage of choice
Step 3. Apply Lid and insert straw through both lid, and mouth of can. Suddenly, you are just drinking a soda. When beverage is empty, remove can and reinsert freshie can, lid and straw. Swap that clip son.
*EDIT- More good strategies and devices for covert boozing HERE