Update (30JAN2015): updated facepaint mesh shirt option to initially show a preview icon of a shirt rather than a face icon like regular make-up. I was unable to get it to show for all swatches but it'll at least make the shirt option stand out under that category now. You'll find it in the .zip I re-uploaded for the shirts.
Update (29JAN2015): added a 2nd .zip file that also contains mesh/sheer boxer briefs. When combined with the shirts located under the facepaint category they look like a combined outfit.
Revised (29JAN2015): added the blue color shirts.
Here I have created 2 different options for your male sims - mesh shirts for standard outfit wear and mesh undershirts to be worn under other clothing.
You'll find 3 styles:
-large netted mesh
-smaller netted mesh
Each style comes in 4 colors:
I have included screenshots showing some basic undershirt + clothing combinations you can do, what the colors look like, as well as what each pattern looks like as a standalone shirt option.
-for the standalone shirt option you will find them located in the TOPS section
-for the undershirt option you will find them listed under the FACE PAINT section
Both packages are able to be installed together with no issues, just unzip them into your mods folder.
Also, on a side note: I unexpectedly found that female sims can use the undershirt option with no problems, it shows up in their face paint section.