I looked and looked and did not find many patterns for men's under garments. Jalie has a really good pattern that has the trunks, briefs and a thong (not pictured). Ok, so the thing is a no go EVER. But the 2 other options are looking good.
Jalie patterns are created by Jeanne Binet, from Saint-Romuald, Canada(a small town near Quebec City). I like supporting local talent.
Jalie patterns come in all ranges, from the smallest boy pattern to XX Large. This pattern will get much mileage. The paper is very thick and easy to trace. You can download the instructions from the Jalie website. Doing so makes it easier to work with as the pattern opens up and is rather large.
He took an old T-Shirt that was too small (he says it must have shrunk in the wash) and laid the pattern on it.
This was Simon's first time following a pattern from strat to finish. He did a very good job. He was confused at first as he did not know where the diagrams were. The instructions and the pictures are not together step by step. After that he was fine. 
Simon made a small error using the serger on the front flap. He cut too much, but he recovered and fixed it. 
