The 'f' pronounced like a 'v' is a Dutch/German thing. Fart is just fart. Båd would be something like 'both' but with a very soft/rounded(?) 'd' instead of the 'th'.
Wait, are there two different kinds of funny mispronounciations here? I thought he was going for buttfart? Or am I completely missing a point? Damn foreign languages...
The 'f' pronounced like a 'v' is a Dutch/German thing. Fart is just fart. Båd would be something like 'both' but with a very soft/rounded(?) 'd' instead of the 'th'.