As I was painting some boards yesterday before the rain started, "Toi khoung biet" suddenly erupted inside my brain.
In my prior post, I said bic. In Vietnamese, it's not "bic" for understand (or know), but "biet".
That was one of the earliest Vietnamese expressions I learned in classes at the Vietnamese Language School at Monterey, Calif. If our teacher (speaking in Vietnamese) said something we GI students didn't/couldn't understand, we were supposed to say, "Toi (I) khoung (don't or not) biet (know or understand)."
The expression "bic" is probably a degeneration of "biet" or else it's what you thought you heard the Vietnamese saying in Vietnam.
Now that I've cleared that up, I feel much better.
However, if you want to use "bic" it's okay by me, I'll know what you mean.