Several ways. Nuts is nuces (it doesn't have the double meaning I guess it has in your motto though, as far as I know). "Protect" you can take your pick of a variety of words: tueri, tutari, defendere, tegere, protegere. I'd go with tegere which means "protect" but also "cover", and therefore fits what my no-doubt too prurient mind imagines your motto is (among other things) referring to.
Either a singular imperative (tege) or a plural (tegite). So tegite nuces or tege nuces. Reverse the order of the words if you prefer.