Penis extension (sometimes may be referred to or indicative of a prolapse) may result for a number of reasons. It is important when it is noticed that you take note of the time that you first noticed it.
Boys do "floss" with their penis, and many times it will hang out for a while afterward. It should retract within a few hours if this is the issue.
Boys will also sometimes be noted with their penis extended when a female is in heat. This may last for a day or two. If the penis is extended for more than a few hours, you can apply a bit of KY gel (the regular NOT the warming kind) to the penis to keep it hydrated. This is necessary, as the penis will start to become painful and may become necrotic if it dries out. Also, the stimulating motion of applying the KY gel will sometimes facilitate retraction. If the issue persists without any other change in behavior, you can use just a bit of preparation H - this will also help facilitate retraction.
The penis will often hang out when there is a UTI. If you notice any change in the glider's behavior or habits while the penis is extended, it is important that you get the glider to a vet and have it checked for UTI.
Make sure you have an ecollar on hand BEFORE this becomes an issue.