It could be someone missing the ! and hitting the ~ instead and being too lazy to erase?

I know what all the C programmers are thinking...

I like to think it's sort of a full-arm wave, like a multi-armed Hindu deity would offer.

So you see, I had a chance to see Robin Williams in a small comedy club back in the '80s when he was good, and I was sitting at a table right in the front where he saw me in my white cable-knit sweater and, at a moment he was trying to find something to riff on, he pointed at me and said "It's Bill Tilde!" No, wait, he said "Bill Tilden". Okay, then, I don't know what a Tilde is for ~ except maybe a way to mark my textual digressing other than "..." or "-" or "—" or "()" or "[]" ~ but I digress.

~IMPULSE 9

I use it to mean 'approximately', before a number. Am I doing it wrong?

There are a lot of typographic sediments in the US keyboard/ansi, in Latin 1 and Unicode.
Their original use has gone out of practice and thus they've been reappropriated.
I know the ~ as a place holder in a dictionary entry.
I had to look @ up to find out that it was "at the rate of" in an invoice. In Nl that used to be the the French à.

In Latin1 we encounter a lot of diacritics. Like privégebruik, coöperatie, Fußball, niño, garçon, konijn.
There's a whole category that are abbreviations from the time when the typewriter supplanted hand-written business documents like ledgers. @, £, ¾.

When we enter the even bigger room of unicode all hell breaks loose.
More abbreviations ℞, ℃.℡
⎧
⎨
⎩
box drawing ╔═╤╕
ancient emblems ☤ (here be trade), ☨(orthodox cross), ☸ (turn, turn, turn)
☔ (weather forecast), ☄ (end of days forecast), ☕ (weary traveler, here be beverages), , ☿(ancient astronomy), ♋ (astrology in a more innocent age), ♔ (monarchy. No chess really), ♬, ♲ (recycling), ☣ (biohazard), ⚂ , ⚓ (maritime), ⚒ (mining), ⚔ (battle ground), ⚙ (industry), ⚗ (chemistry) ⚖ (juris), ☠ (death), ✂------ (cut here),
new emblems ☭☮

I read that as making a kind of wavy inflection in your voice if you were speaking it.

I have nothing to say about the tilde, but that poem is really sexy.
Seriously, did anyone else think that?