Captain Sir - I have control.
CRM books and allied papers make much of the responsibility of the second in command to advise the captain he is taking over control where it is warranted.
In particular if the captain deliberately presses on regardless at low altitude with a badly unstable approach. Or if he deliberately breaks the minima.
While there is no shortage of advice on the things the first officer must say before he attempts to take control from the captain, there is precious little guidance offered to what the first officer should do should his warnings be disregarded. Taking over control at a critically low altitude will certainly result in an arm-wrestling competition with the potential for a disaster. Few captains intent on pressing on regardless will take kindly to the No 2 attempting to take over and almost certainly the captain would be cross and firmly resist.
There is one action however that can almost guarantee a go-around by the captain - and that is the first officer reaching over and selecting the gear lever to up while simultaneously calling "Landing Gear Up - Go Around"
Desperate times sometimes call for desperate measures. Either way the second in command will be called to account for his actions and he must be prepared to wear the consequences. Therefore the gear up action is a last resort. Unless temporarily medically insane even the most culture driven captain will not deliberately land wheels-up just to make the point that real men don't go around.
Rather than inundate first officers with all the politically correct and warm and fuzzy words they must use in warning the captain that things are going dangerously pear-shaped on short final (see Garuda 737 accident report), it is about time the authors of such material cut to the chase and offer practical if indeed brutal advice on how to save the day. Keep in mind there are some out there that really do think real men should not go around.