A couple more fun ones:

Compose: LLAP = "emoji doing the vulcan salute"

Compose: FU = "middle finger emoji"

Compose: <3 = ♥

You can also type music notes using Compose: # + QeEsf or #: ♩♪♫♬♮♯

Source: https://www.x.org/releases/current/doc/libX11/i18n/compose/e...

edit: minor formatting and describing emojis since they don't seem to be allowed