Using forums you can open scratch in scratch in scratch in scratch in scratch …

why

What?

See this quote for the reason it happens:

CST1229 wrote:

scratchgodo wrote:

(#29)
Snip

The reason this bug happens is because the forum preview is an iframe (basically an embedded web page in another web page). By default, links in iframes change the that frame's URL. They can be set to change the outer page, but it looks like the ST (or the DjangoBB devs) forgot about that, or just didn't do that for whatever reason.

Also you can fit several iframes in one iframe so you can open Scratch up in those which cases you to be able to have Scratch open in multiple iframes.
Source of the quote.

Thanks CST1229 for the quote.