This is a funnel end that is intended to fit over 3/4" SharkBite brand PEX to make an inexpensive Christmas tree watering funnel. There are small channels in the end that allow air to escape preventing a column of air from forming in the pipe and preventing water flow down. No glue was needed to attach it to the pipe successfully.

A 5-foot section of PEX can be purchased at Lowes for about $2.50 at the time I'm writing this (12/22/2018) and filament+electricity cost was approximately $3.50.