Is báeth nech conid- fri robaíth -ruici.

Is báeth nech conid- fri robaíth -ruici.

(is * irresponsible * anyone * who- with * greatly irresponsible one -meets)

Anyone is irresponsible who has dealings with the truly irresponsible.
Anyone is an idiot who consorts with a real idiot.

This maxim from the Laws, quoted in O'Davoren's Glossary, warns that having dealings or any sort, including the romantic sort, with someone who is "báeth" will end in tears. The semantic range of "báeth" includes "wild, reckless, thoughtless, wanton, licentious, irrational, foolish, incompetent".