I did some thinking and I think it is a reference to ‘86ing’ someone which is slang for kicking someone out. I only heard it used in the 2004 Leisure Suit Larry reboot (probably because I have never been kicked out of a bar). 47 is Trump since he is (unfortunately) the 47th president. So basically saying to kick him out.
Thanks for explaining. Using numbers as political messaging is a bit weird. I’d only ever seen alt-right/crazy people do it before with 1488.
Edit: I believe you’d call it a shibboleth