GRRM is the common shorthand for George R. R. Martin, the American author whose A Song of Ice and Fire novels became HBO's Game of Thrones. Short clips of Martin's laugh circulate online as a reaction sound, passed around by fans and meme pages. The exact recording this particular chuckle is taken from is not documented, so it is best treated as a fan-made meme clip rather than an official sample. Its appeal is the persona behind it: when the author famous for killing beloved characters seems to laugh at you, the joke lands harder.