Step 1: Good Oral Hygiene…
Is of course very important. However most mouthwashes have childproof tabs that require you squeeze the cap in the right way in order to open it. It's a little annoying though. I do not have kids in my house so I am comfortable using this hack.
Step 2: Bring Out the Dremel
A cut off wheel on medium speed will make quick work of this plastic.
Step 3: Done!
There we go. A "jail braked" mouthwash.