It is rude to bring out your Hologram Tupac at just any event. He is for special occasions. Hologram Ja Rule is for everyday use.
It is rude to threaten to punch someone over the Internet, in part because you're obviously hoarding technology no one else has.
It is rude to not acknowledge when you see what someone did there.
It is rude to "ship" a fictional couple without first making sure you have packed them safely and have correct postage.
It is impolite to react to a mention of bacon in any fashion other than disproportionate excitement.