Rewrite rule for nginx from Apache

[the_traveller]

I know i'm alittle bit annoying

but can you show me how i must write the rule
the path of the script jokes.php is in the public_html dir
and it should talks the args like that 
jokes.php?j=$1

so in Apache  i used  to make the rule like that
RewriteRule ^Joke/.* jokes.php [QSA]

but i alwayes have the sever error on all of my tries

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,23868,200852#msg-200852