URL constantly results in a badbox

URL constantly results in a badbox

I am trying to insert a long url into a latex document. I'm using hyperref
package to make them clickable. However, Kile constantly tells me that it
results in a badbox. It is strange, since, well, these urls do not have to
look good, so it could split them in any place and it would still be good.
I tried a few solutions, here, on TeX exchange, using URL package, sloppy,
adding some manual hyphenation rule and so on. Nothing works. Sometimes it
produces a different hyphenation pattern, but it is still marked by
badbox.
Is there any sensible reason to do it? I want to show the whole url, btw,
so link shorteners are no good (and they aren't answer anyway.)