Worst one due to my own stupidity was at Glastonbury music festival, flew in from JFK the same day. I felt nauseaus and completely disassociated from reality during my body's night hours. Of course insane amounts of alcohol didn't help the cause.

Another bad one was after JNU-SVO. It's exactly 12 hours difference. Talk about very boring nights and feeling like a hot steaming pile of... during the day.

Thinking back, easiest one was after JNU-PKC. It's 22 or 23 hours difference, so in all reality, it was a simple 1 hours difference in time, just the next day.