Short story: I'm Dutch, my teacher is Irish, the class was in English. Today the teacher used a word that I didn't know. It sounded a bit like "cobbom".

The phrase was something like: "this is just to see if you're /cobbom/". Meaning something like: not stupid, able to understand something. I asked him what it meant afterwards, and he repeated the word for me, but I still didn't catch it. Does anyone of you guys know that word?