Save dynamic page as html from browser. Upload to server as html. Add.htaccess rule to redirect old dynamic page to static page. (when traffic dies, remove rule) Or if you are running WordPress, just install wp-super-cache and when a traffic spike happens, click the "lockdown" button.
Header append X-Coral-Control "redirect-home"
RewriteCond %{HTTP_USER_AGENT} !^CoralWebPrx
RewriteCond %{QUERY_STRING} !(^|&)coral-no-serve$
RewriteRule ^(.*)$ http://your.domain.nyud.net/$1 [R,L]
Or even better, just redirect all traffic with news.ycombinator.com or reedit.com referer (before RewriteRule): RewriteCond %{HTTP_REFERER} ^http://([^/]+\.)?ycombinator\.com [OR]
RewriteCond %{HTTP_REFERER} ^http://([^/]+\.)?reddit\.com [OR]
You don't even have to manually disable caching after traffic dies down this way.