From Wiktionary, the free dictionary
са́ми с уса́ми • (sámi s usámi)
- wasn't born yesterday, not a babe in the woods (lit. we have mustaches ourselves)
- Ты мне наставле́ний не чита́й! Са́ми с уса́ми! «Мы бу́дем жить!» - Б.Лавренёв ― Ty mne nastavlénij ne čitáj! Sámi s usámi! «My búdem žitʹ!» - B.Lavrenjóv ― Don't give me lessons! I'm not a babe in the woods! "We Will Live!" - Boris Lavrenyov
Note: This phrase is usually left undeclined - the masculine сам с усам is also found but low colloquial.