First of all, which girl said it was okay? -__- It's not hygienic or clean. The smell test isn't a good way to tell if you're clean, either. Literally your dick and balls are just sweating in those motherfuckers and making your nether regions STANK. So please bathe and change clothes on a daily basis if you want to not be gross.
You know how those Febreeze commercials talk about going "nose-blind" to certain smells becuase you smell them regularly? That is literally what you are doing with your underwear. There is a horrible smell of sweat, dead skin cells, Eau de You, and god only knows what else. Change your underwear for the common good. And wash your other clothes after you wear them too! And your sheets and towels!
Yes it is eww, was that the only pair that you had or something? It does not matter if it smelled funny or not, the rule is: if you take a shower then you have to change you undergarments otherwise all the microbiota will migrate and it will funk down there, no girl will ever want to blow you then.
Do what the #### you want, if you where a female then I would ask you to go see a specialist.