[Fizzlemizz]

Use a toggle depending on what you want to toggle.

local SomeBooleanVariable -- could be a SavedVaraible to save between sessions.
SlashCmdList.MYSLASHFUNCTION = function(msg)
    SomeFrame:SetShown(not SomeFrame:IsShown()) -- show/hide a frame
 
    SomeBooleanVariable = not SomeBooleanVariable -- toggle boolean variable
    if SomeBooleanVariable then -- and action it
        -- do thing if true
    else
        -- do thing if false
    end
end