Russian ⇄ English

ты ничего не понимаешь в колбасных обрезках stresses
inf.	you don't know something from nothing
vulg.	you don't know your ass from your elbow (ты ничего в этом не смыслишь you don't know anything, used in reference to an uninformed person (in Russian literally "you don't know anything about scraps of cold cuts"))