Here the first idea: shorting the VIX (volatility index).

As you can see in the graph below, the VIX has been trading at extreme low levels for the past 5 and 10 years. A surge in volatility could easily pump up the value of the VIX and provide with some short-term gains.

An ETF you can buy that shorts the volatility index by 2x is:

ProShares Ultra VIX Short-Term Futures ETF

Beware of the high costs of holding this ETF.

As promised I'm holding this ETF myself and money raised on this post will also be invested in the index!