Couple things:
1) my "support" will likely consist of liking things on twitter with the occasional RT, posting about it on goEMAW and being annoying to people on twitter DMs and IRL. I'm (like Bernie!) not even a registered Democrat currently so don't even know if I will participate in the caucus (I didn't in '16) so I'm not sure what he means by "support" but it doesn't probably amount to much anyways
2) I don't know what "down with the ship" means