To grind teeth or chomp.
Most often used as a word that sounds like masturbate but is not.
Person A: "I hate that people who masticate!"
Person B: "Dude, you don't ... you know."
Person A: "Seriously, look it up. It's not what you think."
Person B: "Than what do you call --"
Person A: "Nevermind!"
Meaning to chew, however people who have never heard this word before will think you said masturbate.
"Dude, I got this food magazine with free samples, wanna masticate?"
"Dude, you're sick in the head."
"Dude, what you don't like eating?"
"Dude, I thought you said masta-"
"Dude, yeah yeah, you'll never change."