弱肉強食（じゃくにくきょうしょく）

weak : meat : strong : eat

After a lengthy hiatus, I'm back to introduce a yoji-jukugo so comically well known that quite a few non-native Japanese speakers should have already heard of it: 弱肉強食. Fully stocked with two preexisting 4-word translations, 弱肉強食 is defined as the "law of the jungle", or the "survival of the fittest". Han Yu—arguably known as the Chinese Shakespeare of his time—is credited with coining this term in his literary work, Preface Seeing Off the Buddhist Wenchang. 

This particular yoji-jukugo has been indoctrinated into a group of comedic Japanese known as proverbial parodies. Some of these parodies take advantage of homophonous kanji to change the meaning while preserving the pronunciation—such as 馬子にも衣裳 (まごにもいしょう, "anyone can look good with the right clothing"), which can be hilariously miswritten as 孫にも衣裳 (same pronunciation, "even your grandchildren can look good with the right clothing"). Meanwhile, others change a few words here and there while keeping the core rhythm of the expression intact: for example, 寄らば大樹の陰 (よらばだいじゅのかげ, "If you seek shelter, look for a large tree") has been given a not-so-subtle edit to reflect modern sentiments in business-era Japan as 寄らば大企業 (よらばだいきぎょう, "If you seek job security, work for a large firm"). 弱肉強食 falls into the latter of those two categories, thanks in large part to a slight formatting flop in Japanese standardized testing a couple decades back. 

It is common in Kanji Kentei to test yoji-jukugo proficiency by omitting one or two kanji from the proverb and asking the participants to fill in the blanks. In the latter half of the 1980s, 弱肉強食 was often depicted on tests as ○肉○食, tricking children across the country into foolheartedly writing down 焼肉定食 (やきにくていしょく), or "set meal with grilled meat". It became such a common mistake that critic Hideo Okuma included it in his book How to Write Understandable Japanese (unofficial title translation), noting that he was struck dumbfounded when students provided no explanation other than "that's all I could think of".

Playing along with the proverbial parodies (and since we already have two fully functional 4-word translations of this proverb), I'll make a couple puns out of this one.

My attempt at two parodies of 弱肉強食（焼肉定食）

Survival Of The Fattest

Law Of The Cafeteria