A sentence followed by the '~' symbol is meant in sarcasm. This is vitally important, because a lot of confusion is caused by sarcasm over the internet by typed words.
~ already means 'approximately,' which essentially means so-so: *hand motion tipping back and forth.* Therefore, we can see how it relates to irony/sarcasm: it means, "Just kidding, but sort of... no really I'm kidding... buuuuut"
"Of course the other definitions of '~' are going to be commonly used by people...~"