You lie, and no one's buyin' it. That's not true - some people are. But I'm calling your "30-incher" about 19. Unless you have been diagnosed with bozoenae digititus (common name: clown fingers), that fish isn't as big as you'd like us to believe.
What. It's true.
But that's okay because ultimately, dishonesty as much a part of fishing as foul hooking and hero shots. Otherwise upstanding people lie like whitefish under a foam line. And that dishonesty can maintain fishing friendships well beyond truthfulness. Be it an agreed-upon "rounding up" of inches, misleading directions to the honey-hole for the uninitiated, or outright lies about where you've been, fishing lies can show your angling integrity.