My mother loves the Viking pigs doing "In the Navy." She says she nearly died laughing the first time she saw it...and I get quite a few cackles out of it, too. I think the writers liked having the pigs engaging in evil, tyrannical (but screamingly silly) acts.
In fact, I find the opening long shot of the ship with the pigs in their Viking helmets to be hysterically funny. Don't ask me why.