I used VE in Firefox 21.0 on Ubuntu to edit https://www.mediawiki.org/wiki/Backporting_Fixes . I changed a few headings, then pressed Enter between a heading and a numbered list below it to insert a new line (not sure if the caret was on the end of the heading or the start of the first item, I'm not sure if I started typing.
VE began inserting the first sentence of the numbered list but with its link changed to two snowmen, about 15 times. Every time I clicked it would prepend some more. Even scrolling would trigger this.
Before, the document contained
WMF Cluster Backports
Make sure there is a bug registered in [[mw:Bugzilla|Bugzilla]] for the issue.
I couldn't edit the document, but VE's review and save button worked fine. The new document showed as
Make sure there is a bug registered in ☃☃ for the issue.Make sure there is a bug registered in ☃☃ for the issue. <repeated 269 more times>Make sure there is a bug registered in [[mw:Bugzilla|Bugzilla]] for the issue.
I don't know what happened to the heading, I didn't blank it out. I might have attempted a cut and paste, maybe that's what's going haywire, though I'm pretty sure the last thing I did was pressed Enter to add a sentence after the heading.
I assume this is an Easter egg in the VE codebase: if you manipulate the document near an exhortation to file a bug, Parsoid detects it and repeats the phrase, with snow people 8-)