You will need the shirt & sleep shorts combo mesh from
here for these to show up in your game.
Here are 8 pairs of pj's/undies for the bodybuilder, consisting of a loose t-shirt and sleep shorts.
They are organised into 2 sets with 4 outfits in each set.
Set 1.
Set 2.
Credits:
Mesh - Marvine and Beosboxboy