Last time I went to Nepal for my brothers marriage I took 15K cash with me and believe me it was big problem from start. It happens that you are only allowed to take max 10K in cash when you leave the US, so I had to go through a lot of hassles just getting out of the US. Explaining to them that I am taking the money for my brothers marriage. I had put the cash in my carryon and they must have detected that during baggage x-ray because they stopped me before boarding and checked all my stuff in detail. Anyways to cut the long story short, it's never a good idea to carry cash. If you absolutely have to, keep it in your pocket because I don't think they can detect it on you. In the carry on, they could see what seems like a stash of cash and they can check it out. After the hassle during leaving the US, i put the money in my pocket the whole time. From next time I'm just going to do bank transfer. Not worth the hassle. If I had been caught in any of the stop overs, they could have confiscated the money. Thank god i got off easily from the US customs.