Just a few comments as a genuine "user":
(1) Don't assume users are plain stupid. We often aren't. But also don't assume we know all the acronyms and technical terms.
(2) We may, however, be very scared of letting you know we don't know the latest acronyms. If we don't understand something, we won't ask straight away, because we don't want to look stupid. We'll often wait and see if it comes clear. Frequently it doesn't, and then we find we can't ask because we've left it too late...
(3) It may help if you try to establish what sort of level of knowledge we do have. For example, if you're explaining something that involves entering data into a table, how we expect it to work will be greatly influenced by whether we're deeply into Word tables, or a keen spreadsheet user.
(4) If you demonstrate something, do it reasonably slowly so we can follow. IT experts who lean over your shoulder, tap frenetically at the keyboard for 15 seconds, lean back and declare "There you are!" are missing the point: there we aren't.
(5) If you honestly don't think we need to know something, explain why, without patronising. If we still want to know, treat it as curiosity. Anyone who enjoys their subject should enjoy satisfying others' curiosity about it.
(6) And if you do think we need to know something, be a little tactful about how you introduce it. A crude example from 15 years ago that I still remember with shudders: as we're nudging a piece of drawing exactly, carefully sideways using the cursor keys, it really doesn't help if the IT expert leans over a shoulder, grabs the mouse, and throws our drawing six cm across the page with the words "You could use the mouse, you know!"
And a final note: quite seriously, if you find that your users want to know something, and your manager wants you to explain it, but you can't see the point, then maybe you should be thinking about whether a sideways move into a different role would be appropriate, should the chance arise.