You really don't know what a swear jar is? Swear Jar is often put on the table at work or coffee shop by the "preacher" (not literally a preacher think nickname) or religious guy for folks to put a quarter or dollar in every time they swear or cuss. As that person, it isn't a surprise.
Actually, no, I never knew what a swear jar was. In all the places I've worked in my lifetime, none of them had one.