I used to have a lot of dull (simple black or grey) underwear and socks... but I have cleared most out and bought some nice new stuff in nice colours (it is quite difficult to find mens underwear in anything other than black/grey/white or dark blue)
I have done the same with socks except with more and brighter colours... I think I may be developing an "interesting sock fetish".
I have a pair of stripy multicoloured socks that go above my knees, and they were only £2.