Hi @davidvm. It may be possible to get a jquery plugin to do this, or you can use some custom jquery, Webflow allows you to use jQuery in your site, you normally put that in the Footer of the site : Custom code in head and body tags | Webflow University
If you can live without having it random until we have a chance to make an option for this, the slider and lightbox widgets may be the best simple solution.
I hope this helps. If not, please let me know – I’m happy to assist further! 
Cheers,
Dave