For Regulation Crowdfunding, you are allowed to talk to the public about the facts of your business or products if you do not mention the terms of your fundraise.
The SEC's final rules on Regulation Crowdfunding are clear on this point:
In addition, the final rules do not restrict an issuer’s ability to communicate other information that might occur in the ordinary course of its operations and that does not refer to the terms of the offering.
If a stranger walks into your store and chats you up about investing, feel free to answer their questions about your business. Don't say non-factual things like: "We're the best cupcake shop in the world and we're gonna be HUGE!"
If they ask about terms of the offering, you must point them to your Wefunder pitch, and they can only make an investment through Wefunder. You cannot accept money on their behalf.
For "Demo Days," you can mention you are on Wefunder during your presentation if you keep your presentation limited to facts and say nothing about the terms. Most credible demo days – such as those organized by Techstars or Y Combinator – already do not let their participants mention they are selling securities (or the terms of their offering) so as to not be deemed a "general solicitation" of securities that is forbidden for most Regulation D offerings.
That same rule applies for conferences. You may mention you are on Wefunder if you limit your discussion about your business to facts and do not mention the terms.