MediaWiki:Common.js

var today = new Date();
var month = today.getMonth() + 1;
var day = today.getDate();

var prankMonth = 10;
var prankDay = 12;

var pageName = mw.config.get('wgPageName');

if (month === prankMonth && day === prankDay) {
    if (
        !pageName.startsWith('AF:') &&
        pageName !== 'MediaWiki:Common.js'
    ) {
        window.location.href = '/wiki/AF:' + pageName;
    }
}