Going to sound so stupid but...

What I always got out of the Thai Makanan remark is just that Thai Makanan smells salty; when people have sex, they sweat. So I guess her crude remark was just to state that the air smelled salty with sweat, which is what Thai Makanan smells like.

"F*cking", which could be spelt like Foking, which is kind of Thai-sounding when anda say it. xD So when she berkata "It smells like Thai Makanan - have anda guys been f*cking?", the f*cking part is tying in to the Thai part.