A conversation filler which most times suggests a hypotheticalsexual innuendo or anything risque. It is not meant to be understood or even have to do with the subject whatsoever.
A phrase that began on Tumblr as a caption for any picture of an extraterrestrial, ostensibly because that is the only thing an extraterrestrial ever says. Since its Tumblr beginnings it has come to be used when referencing any unattractive female, particularly one so hideous as to resemble an extraterrestrial herself.
Rupert: Did you see the girl I was with last night?
Dave: Ayy lmao!
Rupert: Dude, she wasn't <i>that</i> ugly.