Essentially meaning 'I'm just saying', 'just casually' is most often placed at the end of a sentence, often preluded by an idea or statement that is commonly accepted as truth. As a result, it is most often used following an observation. 'Just casually' is a light phrase that connotates feelings of ease to others, as it often has the effect of putting less emphasis on the matter/issue at hand.
Kim Kardashian is totally hot, I would so do her if I could, just casually.
#btw#by the way#in other news#just saying#i'm just saying