Buy a longer cord instead.

You really shouldn’t daisy-chain two extension cords. Every connection is a point of failure, and the voltage drop can make things weird or dangerous. If you absolutely must, use the same gauge (12 or 10 for heavy loads, never 16) and keep the total length under 100 feet. Never run them through doors, windows, or under rugs. But honestly? Spend $20 on a single cord rated for the distance. It’s safer and saves you the headache of wondering if the junction box will melt at 2 AM.

Future you deserves better than a melted cord.