The option market was pricing in about a 12% move. Today we got a 15% down-move. This means that anyone who was short puts either has to cover or they have to sell stock to reduce risk.
Normally what happens after earnings events is that the implied volatility gets crushed as the event risk goes away. However because the options market is feeling a bit of a squeeze, the IV remains elevated... this was the case this morning, but less so right now.
So the trade? If you want to buy the dip, I would look at cash-secured put sales. Specifically the Sep 21 put sale for about $1 or higher.
If fb heads under 21 bucks then you will be assigned with a basis in the 20s. From there you can roll to covered calls or just hold onto the stock at these levels.
Put sales make sense if you are bullish stock and bearish volatility, and as IV continues to fall as the event risk goes away, your position will be in an advantage.