Yeah, you can use your imagination there. In one context, that sign can in fact mean "to appear," and in another it can mean, well, to insert something.
Hey, remember that crazy story of a dangerous attempted murderer getting on stage with President Obama because he pretended to be a sign language interpreter for Nelson Mandela's funeral? And how it turned out it wasn't even the first time he'd done that? That happened because so few people know a damned thing about sign language that a crazy guy making random hand motions fooled the security details of multiple nations' heads of state. And while that's just an oddball story to you, this is the kind of thing that can ruin a deaf person's life.
Let me give you a less hilarious example: I have a friend whose sister is deaf. She was in the hospital for a simple operation, and the sign language interpreter, like many, wasn't qualified to be doing it and accidentally told her the doctor had botched the surgery. When my friend arrived, her sister was tearfully saying her goodbyes. And if you're wondering how you could accidentally convey something so radically incorrect, see the "tampon" situation above.
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"I swear I was just talking about astrology."
Translators now have a national registry and a professional code of conduct, but, obviously, progress is slow. Many organizations don't have things like "ASL tested" or "vaguely qualified" people, and that can lead to screw-ups in pretty important places. Like courtrooms. Cases have been thrown out after the judgment when the tiniest amount of digging revealed that the interpreter wasn't qualified and botched the interpretation. Imagine if the lunatic from Mandela's funeral wound up translating your testimony at trial. And even when the interpreter knows what he's doing, legal interpreting is complicated as hell -- something like the Miranda rights can take up to 20 minutes to get across. The potential for disaster there is huge.
All of this means that ...