Hugh Jackman went commando in X-Men: Days of Future Past because it's the Australian way.
In the film, Jackman's Wolverine is whisked into the past, emerging naked in bed with a woman laying next to him. But as the scene was originally written, Wolverine was to be wearing boxer shorts:
"I land back in 1973 - this is what the script says - I wake up next to a girl who I don't remember, and I get out of bed wearing boxer shorts. I was like, 'I don't know about America, but in Australia if you're next to a really good looking girl, you're not getting out with boxer shorts on or briefs or anything.' So yeah, I went commando. [...]
They bought a bright green sock for me to wear and I was like, this is kinda drawing more attention than less. They said no, we need bright green, like a green screen, so if you bend over or turn around, and we need to erase anything, we can. I said that's even weirder. They said please put it on, but the end of the first take I was like 'Ermm, it's gone, I don't know where it is.'"
Bless his dedication.