COM_AddCommand("_multiability", function(player, answer)
    player.multiability = tonumber(answer)
end)

local cv_multi 

cv_multi = CV_RegisterVar({
    name = "multi",
    defaultvalue = "on",
    flags = CV_CALL,
    PossibleValue = CV_Onoff,
    func = do
        if cv_multi
            COM_BufInsertText(consoleplayer, "_multiability ".. cv_multi.value)
        end
    end
})

addHook("PlayerThink", function(player)
    if player.multiability
        player.skinflags = $1 | SF_MULTIABILITY
    else
        player.skinflags = $1 & ~SF_MULTIABILITY
    end
end)