Solar Light Stake with half-threads on each half of the stake, I think originally from Costco but unsure of brand.

Threads were captured with the Revopoint Mini and the scan file is included should you choose to build your own variation. Rest of the geometry was done up in Tinkercad real quick so not the prettiest but threading and unthreading is smooth but tight once you bottom out the threads.

Print Orientation and Info

Print this with the cylinder facing down with supports. I recommend doing painted on supports around the perimeter like so

This will keep the supports away from the threaded portion, your sliced preview should look similar to this