Depend, the human
toilet company, makes plenty of
products that make
taking a crap as easy as blinking your eyes.
They make maxi pad-esque liners, "undergarments", which are sorta like diapers with thong straps, and briefs! Everything you could ever need to provide a little security in an insecure world.
But, guys, aren't they forgetting a key market? Yup! Boxer shorts! There are tons of guys and even a few non-guys who wear them religiously, and would never think of going to tighty-(insert color here)ies. Designing Depend boxer shorts would take some engineering ingenuity, since boxers have open space at the cuffs where the urine and feces could come pogoing out!
Why not seal them off inside? You could have semi-brief liner that would still provide the comfort of the boxers, without turning your khakies into blue jeans (or whatever your urine and fecal matter is colored.) You could even have smilies, hearts, polka dots, or even cute little i-Openers on them! If I were old and squirtin', or if I had a septic tank that clogged, I'd buy them in an instant!
Depend, because you've got a lot of living to do!