look up any word, like ratchet:
 
1.
when the ratio of girls to guys exceeds 5:1 the room is considered as ratto.
hey man there's a stupid amount of girls!, its completely ratto in here !!
by Big-Bird-23 December 26, 2012
 
2.
Australian slang for rat-faced. To get ridiculously drunk, so as to look like a rat.
Mo: Hey douche, you going to the party tomorrow?
Jez: Hellz yeah, let's get ratto!
by Blobs October 12, 2011