SJW is short for Social Justice Warriors, but they are used to typing it in social media platforms so they needed to abbreviate it. So SJWs are Social Justice Warriors who are too lazy to actually do anything except let everyone know how "Woke" they are from behind a keyboard. Actual Social Justice Warriors march and protest, and practice civil disobedience, while SJW's just tweet about it. There is a proud tradition of Social Justice Activists that is being cheapened by the current proliferation of trendy SJW behavior. Be a Social Justice Warrior, not an SJW.
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.