You can hit him in the groin with a banjo

Eric:
Hey, dad, um, I was wondering if you could show me, like, a few fighting moves. Red:
Who you planning to fight? Eric:
David Milbank. Bob Pinciotti:
David Milbank? He's got scoliosis and asthma. [pause] Bob Pinciotti:
You could take him. Red:
Oh, come on now, Eric. Why don't you, uh, beat up Kelso? I don't work for his dad. Eric:
He's making a move on Donna. Bob Pinciotti:
Oh, no. No. No. Donna's not going near that pretzel boy! No. No. You gotta nip this in the bud, Eric. Red:
All right. All right. The bridge of the nose is very vulnerable. Bob Pinciotti:
Oh. Oh! And hit him with a banjo! Red:
[pauses and stares at Bob]
A banjo, Bob? Bob Pinciotti:
What? I'm helping! Red:
Where's he gonna get a banjo? Bob Pinciotti:
I don't know! But I saw a guy get hit with a banjo once, and he went down. Red:
[pauses and stares at Bob again]
Hitting a guy with A banjo, is dirty. [to Eric] Red:
You wanna knee him in the groin. Bob Pinciotti:
You can hit him in the groin with a banjo