There's nothing like biting off more than you can chew, and then chewing anyway.

When I testify, I'll testify. I don't need to sit around chewing my fingernails.

I bite my nails. I've been chewing on them for years. As long as you don't chew through flesh it's all right.

Don't bite more than you can chew.

He leaned down until his lips brushed her ear. “I told you to stop flinching.” And then he bit her. A slow, painless nip but there were definitely teeth involved.

[But he enjoyed his first afternoon in the Swamp, anyway.] I was actually chewing some kid out when I looked up and saw everyone was swaying (to music), ... So I just stopped and listened ... then I went back to chewing him out.