いい加減にしろ
いいかげんにしろ (iikagennishiru)
That's enough! / Cut it out!
No verbs allowed, remember. Also, that's a whole sentence, not just one word (ii ka gen ni suru, if you were to include spaces). And a quick grammar note: I believe the correct form should be する, not しる (since it's the verb する, to do). You normally hear it as しなさい in this phrase.
It's not a する verb. It's not even a verb. It's an expression, and the only kanji in it (加減) operates as either a noun or a な adjective, depending on the usage. Also, the しる part is not part of any verb, it is part of にしろ, which means "even though" or "whether". 
But I didn't know expressions weren't allowed. My bad!
Are you sure? I've never heard of the word にしる, and I just tried looking it up, but it's not listed in the dictionary either. There doesn't seem to be a word しる either (apart from 知る and 汁).
My understanding of it was いい加減 (a noun, which in this context means reasonable, or moderate) に (particle) する (to do). Literally meaning, calm down, be reasonable. In practice meaning "that's enough", or "cut it out". I could be wrong, of course, but that's the way I've always understood it. Since it's usually only used as a command, it's generally in the form しなさい or しろ, rather than する - could you have misread/misheard しろ as しる?
