Automate standard replies

[Francesco Ariis]

Hello mutters,
    how can I automate typing standard replies?

Example: say I want to type «lgtm» (top post) as a reply to a message,
as now I have to:
- press `r` (reply)
- press `i` (my editor is Vim)
- «lgtm»
- then <C-[> (exit insert mode)
- ZZ         (exit/save file)
- finally `y` to send

Is there a way to one-button this? I thought about a macro,
but I suspect that wouldn’t work, since I am firing up an
editor.
Thanks in advance
—F