US Global Jets ETF has already declined by about 10% last week and options traders are betting it goes even further. They were buying the August 27, $21-strike puts when the stock was trading just above $21. Najarian decided to follow the trade.

He has also noticed some bullish call buying in Skillz Inc (NYSE:SKLZ). The August 27, $11-strike calls were active in the name. Najarian bought the August $10 calls and he is hoping to sell upside calls if we get a move higher in Skillz.