This happens to me sometimes when I'm on my own. 20 tables free, a 100 feet long 50 feet wide space, and someone comes and sits within 6 feet of me. I have actually got up and moved to the other side of the cafe/restaurant before now. I don't care if it offends them.
As you say @FattyAirways WTAF are they doing sitting right next to you anyway, when they could choose a table 50 feet away? Happens in the cinema too. 500 seats - and only 20 people in - so 480 seats to choose from, and someone still sits on MY row, 2 seats away from me, or directly in front. AGAIN I will move.
Went into a cafe once with a colleague for a lunchtime coffee, and there were 40 tables available. Only 5 were occupied. (Including ours.) Some random man just sat right next to us with his frappuccino and brownie, even though he had 34 other tables to choose from. My colleague was talking about something to do with her children, and was giving an opinions (about whether they should be on reins or not when they're toddlers...)
This man started chipping in on the conversation, and adding his twopenceworth! Saying he disagreed with her opinion!
She was like
and then
Grabbed both our drinks and said 'come on Ebony, grab the cakes! Time to move to another table, where nosey prying ears can't hear our PRIVATE conversation!'
Cheeky fucker! 😂 Totally unwanted and unsolicited butting-in, on the conversation of 2 strangers. Who DOES that?