I would clearly remind them of the differences between stocks and cryptocurrencies, which have some properties of stocks (especially small speculative stocks), some of commodities, and some of currencies.
Yes, this is a frequent source of discussion: this is not a stock - this is fundamentally a new form of money itself. It is a new financial universe that must expand to be useful, and for it to expand it must go through a speculative tier where people are "buying the colorful beads" because they predict others will eventually want to use them to transact with. Obviously, the potential for cryptocurrency goes beyond a simple stock. At it's best, a stock will only achieve dominance of the speculative tier - there will never be a transactional economy using stock certificates, and on the flip side: a cryptocurrency almost certainly needs a transactional economy to emerge in order to maintain legitimate long-term value if it is initially backed by 'nothing'.
As well, I make sure to mention many reminders of the risks involved and that money transferred into crypto-assets is "as good as gone" (so pretend you've already lost it).
It's not exactly '4dummies' but paper wallets can certainly be created offline with simplewallet (even without having a daemon running). Proper paper wallets for all coins have always required a bit of extra work, but are still important for secure long-term storage.
Thanks for the tip.