The male Na'ví "Private" area

[Skxe Eywaftu]

Was wondering, I watched the movie again, and based on the Na'ví size and the small under garments, and the lab coat Jake was wearing near the beginng, does "it" like stay inside them until its kind of needed? Like when two kangaroos fight, they retract theirs, same with sumo wrestlers.
Thoughts?
P.S i didn't use the actual naming of the certain body part (possible minors), but i hope that you got the idea

[Tìng Eywatikìte'e]

Please re-ask this question in the Na'vi Biology thread as it falls under it and isn't enough to create an entire thread off of. Thank you.