People are using avocados to propose. Instead of a ring box they're sticking the ring in the avocado where the pit goes. Obviously, they're also posting about it online with the #avocadoproposal. Click the link in the tweet to read more, then scroll down to see more examples.
If you're not an avocado lover you might think this is ridiculous, but on the plus side I've typed the word "avocado" so many times for this story, I will finally remember it's not "avacado".