starter and knock sensors on a 4.5L infinit v8. Fuck you Nissan.
Front diff bushings on the 5.7L grand cherokars around 04 to 07 give or take.
Accessory drive belts with pulleys so close you can't fish a new belt in without removal of the pulley. Looking at you 6.7L cummins.
Engineers that leave you room to install a space for an expansion, but not enough space to maintain either in a treatment plant.
process engineers that create a problem and then want more money to fix it because the new problem wasn't in their scope of work originally.
Honestly, I want to stab the fucker that designed (yes I know who it was) the rear takedown retention spring location on the AR. I mean really 2 extra seconds could have seen a shorter spring and a threaded in cap...but no, lets not make it simple. I bet the same fucker thought it was a great idea to use a roll pin for the bolt release rather than thread that.