Usually it is used by fangirls to express love over a specific character in an anime or a video game
Also it occasionally starts or ends with a word.
"FGHDSJAKFGADSJKGHFSAJLDGHFSKLDAGHYES I DID!!! IT WAS SO AWESOMEGFDJLGHLKDGKFAL *foams at mouth*"
The uncomprehendable words the second person was saying is an example of over-excitement typing