First, find a tightly sealed jar. You know the kind. Just look at this smug asshole; thinking he's tough shit.
Fuck you, jar.
Now, get a knife. Any knife will do. Jam it in under the top of the jar. Yeah, you like that, bitch?
Now push it outwards, away from the jar. You will feel the air pressure inside the jar normalize, and maybe even hear a small pop as the top is now open.
You can now easily open your jar. Enjoy that shit.