This is an age conversion of teen plaid pants made by .laetitia. I think her idea and execution are absolutely stunning, and I really wanted the pants for my adult sims. With some help of the very friendly VioletPadfoot I was able to convert the teen pants into adult pants using the classic untucked/tucked mesh by HystericalParoxysm.

Link to the original teen pants by .laetitia; http://www.modthesims.info/d/258958

I have used .laetitias texture for the pants, but the shoes are from frizelbliz. Full credit to these two for all the actual graphic work and the ideas, I've merely put it together in this particular form.

There are 6 colors (red, blue, green, purple, orange, mixed), all available in both untucked and tucked versions. The shoes are the same black sneakers for all versions.
The files are all properly named and easy to distinguish, so if you don't want all colors it's very easy to grab only the ones you want.

Found in everyday -> bottoms.

The mesh you need is called MESH_AF_B_SlouchypantsBoots, and can be found here;
http://www.modthesims.info/download.php?t=228762


CREDITS:
.laetitia for the texture and the original idea (http://www.modthesims.info/d/258958)
HystericalParoxysm for mesh
frizelbliz for shoes (http://www.modthesims.info/download.php?t=251468)
VioletPadfoot for the instructions on how to actually do this

Programs used: Bodyshop, Paint

The shirt seen in the picture is by sga_girl and can be found here;
http://www.modthesims.info/download.php?t=429985

Additional Credits:
.laetitia
frizelbliz
HystericalParoxysm
VioletPadfoot