ecco la

I didn't even give it a second thought. Italian ecco la is kinda like French voilà (lit., 'see there') and voici (lit., see here'). Latin has ecce (as in Pilate's ecce homo 'behold the man', though also translated as 'lo, the man'), and I assumed that Italian ecco had something to do with that. The word deixis seems à propos here.

Ceci n'est pas un seing.