There are plenty of godawful ninja battles out there, but this scene from Female Ninjas 3: The Magic Chronicles takes the cake. Two ninjas are enjoying astral projection whoopee, when a bubble from the netherworld emerges from someone's nether regions.
Mind you, this isn't the only kind of uterine ninjitsu in Kunoichi ninpô chô III: Higi densetsu no kai. In this sequence, the bubbles have the power to transform men into babies trapped inside giant polyurethane globes.
Apparently magic goes beyond simple force field production. I'm not sure if this clip is from the first, second, or third Kunoichi ninpô chô, but apparently the human cervix can absorb and rechannel magic blasts. Thanks for nothing, 9th grade health class.
Youtube user Sandronicus1313, who uploaded the first two clips, has a prime selection of insane kung fu and ninja duels. My favorites are the video game chi battle from Buddha's Palm...
...and this absurdly intricate Mousetrap-like prison from Shaolin Drunkard.
[Spotted on Nerdcore. Also thanks, SupaChupacabra!]