Please stop asking! Your wish has already been granted (perhaps at the next website update).
Hug Your Dog
Take a photo of a beer
Take a photo of a sleeping animal
Agreed. So much for bringing back virtuals without bringing back their problems. What's this got to do with geocaching? Please move it to another site like Waymarking.
Virtuals are great. They actually involve you going somewhere specific and learning something you would otherwise miss.
Challenges are not "bringing back virtuals" but rather bringing back Locationless caches, which, let's face it, sucked. The new "Challenges" feature on geocaching brings back exactly the problem that was solved when the Waymarking website was created. I completely agree that in their current state Challenges need to be moved to Waymarking.com.
HOWEVER, I have actually completed one of the older challenge caches and have started attempts on a few others. I think Challenges are great, if performed correctly. The "Hug Your Dog" challenge is not performed correctly.
Of course, the old rules on posting a Challenge cache specifically directed the poster to create something challenging (go figure), the new feature does not have any real rules in the FAQ. This can be solved by directing all those Premium Members to the proper resources before allowing them to submit a new Challenge:
Everyone should be required to read this info on Challenge Caches
So... Using groundspeaks example of "Kiss a Frog", I think that we can safely forget about any requirements of making it a "challenge".