Growing up I remember hearing ads for action figures that had “kung fu grip”… what the hell was it?
The way GI Joe’s hands were moulded so they could hold stuff, like their weapons.
This video explains it.
From Wiki:
Essentially, you could bend the fingers around stuff.
You could see exactly how the hands worked in the commercial. Thanks to YouTube, you still can:
You didn’t bend them around something, but they were flexible rubber. You could hold them open, put something in the palm, and release them. They’d go back to their natural position, and hold whatever you had placed in them.
I read the G.I. Joe wiki doing a search for Kung Fu and I didn’t see that! I swear I looked!
You are correct. I take that back. The hands are more like springs.
Oh, this isn’t about song lyrics. Never mind! 
Heh. I didn’t know anything about a song with that title, but judging from the title and comments at that YouTube link a lot of people arrive at the page under the impression that it’s that video.
I can fix that.
From Little Skipper, by Andrew Ratchin. (A song about Barbie’s little sister going out with G.I. Joe)
And Skipper wants to dress herself in leather
But Skipper needs assistance to unzip
Joe is armed and ready, willing, able
With his trusty hand-grenade and kung-fu grip
I was hoping someone would post something to which I could reply, ‘Oh, that was sublime.’ But since someone doesn’t know about lyrics:
*So she told me to come over and I took that trip
And then she pulled out my mushroom tip
And when it came out it went drip drip drip
I didn’t know she had that GI Joe kung-fu grip *
I was thinking of something a little more “Sublime”.
I like mine better.
I loved that they worked a joke about this into the live action G.I. Joe movie.
“Hey bro, you got some life-like hair over there… oww, and a kung-fu grip!”