Ahahahahahaahaaaa!!!!:
"A gentleman is mostly likely to fart first thing in the morning, while in the bathroom. This is known as "morning thunder," and if the gentleman gets good resonance, it can be heard throughout the household."
I am literally LOLing at this page - the writing style of the guy is brillant :D:D
Plenty of ladies get that too, usually it happens at the same time as the first urination. because you are lying down overnight the gas is more likely to move down the digestive tract so its waiting, the extra pressure from the number 1 expells it.
IIRC the idea that most farts involve air you have swallowed isnt true, most of that ends up back out via burping and the rest is absorbed through the small intestines. Fart gas is provided almost entirely by bacterial action in the large intestines.