I talked to the guy who did the interview a month ago and told him about the problem and advised him to change it to why.usesthis.com and his last words were "you know, i think i might do that. :)" So.
Thanks to the code:
get '/interviews/:slug/?' do |slug|
@interview = Interview.first(:slug => slug)
raise not_found unless @interview
haml :'interviews/show'
end