I'm leaning towards sneezing. If you bring a nice lady out to dinner, and fart every two minutes, she's not going to be very impressed. If you had to explain the situation for her, she'd probably be more sympathetic and more understanding towards the sneezing.
However, I'd have to look into the side effects of sneezing that often, too.
But, nobody ever said how loud you have to fart, and I've got my long-term girlfriend, so it's not like a new relationship where first impressions are everything, so I'ma going to go with farting.
...Would you rather spend a romantic evening with Kathy Grifin or Amy Winehouse?