You simply push PEX pipes and fittings together rather than gluing (PVC and CPVC), soldering (copper ... like cleanout plugs, are threaded. Here are the most common drain fittings.

the intended purpose of the PVC pipes. But [John] tipped us off about FORMUFIT PVC Fittings designed for construction use instead of plumbing. There’s a lot of interesting options, such as the ...