1. Using the word "like" as a placeholder for your sentence. People who shoehorn "like" into the same sentence four or five times are so committed to not listening to you, that they spoke before thinking out their response and the "like" is simply buying time for them to think of what to say next. These people talk for their health.
2. Using the word "literally" when there's no figure of speech at play. Holy fucking God I hate this one. People under 25 have such poor rhetorical skills, they have stripped all meaning away from this word to create in its place another way to connote emphasis. Now all "literally" means is "I REALLY mean it so please listen to me"
3. The word "but" altogether. "And" is additionally, "or" is aternatively, "but" is always followed up with some absolute contradictory horse shit.