Public speakerphone talkers.
If someone is near me using speakerphone in public and I am with someone, I route the conversation to something awful and speak loudly.
If I am alone, an extended coughing/throat clearing/snuffling/nose blowing will suffice.
Another is physically capable lazy fucks who park in front of the door at gas stations or coffee shops rather than an actual parking spot.
If they are even slightly overweight I will comment "you know, parking and walking can help with your obesity issue". If they are fit, I fall back on asking what their handicap is physical or mental.