When you see or hear something g funny (not too funny) and it causes you to push air out of your nose at an abnormally fast rate in place of a laugh... a snicker with your sniffer, if you will.
That dank meme on ifunny made me sniffcker, but it wasn't funny enough to make me actually laugh.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi