This may be a little too obvious, but what about a few demonstrations of inexplicable barroom physics...
Being a "garage physicist" one could assume that Bob enjoys playing pool because there's a good deal of physics involved in the game. Bob decides to invite Alice out for a few games and more than a few drinks.
After they order the first round, Bob offers to pay, but the bartender refuses to take his money. Alice thinks that Bob set it up in advance, but isn't too concerned about the free drinks.
They play their first game, Bob wins, but not through any extraordinary event, he just plays a little better than Alice. Bob begins to rack the balls and offers to let Alice break on the next game.
Alice breaks and inexplicably every ball on the table bounces into a pocket. She immediately assumes that Bob has conspired with the generous bartender and rigged the table. He laughs and assures her that there is no grand conspiracy and offers to rack the balls again.
Alice refuses to let him rack and starts to collect the balls. She takes her time examining each ball and allows them to roll across the table watching for any peculiarities. Bob offers to break, but Alice again refuses.
Alice spots the cue ball and hits it hard, really hard, it flies across the table and bounces off the 1 ball with enough force to send it flying back into a corner pocket, but none of the other balls on the table move at all.
At this point, Alice is fuming, but Bob laughs it off, takes the cue ball in hand and citing the rules of the game places it behind the head string and hits it. The cue ball again flies across the table, but this time only the striped balls bounce into the pockets, leaving the solid balls completely untouched, still in formation.
Alice groans, but being curious at this point, lines up and takes her shot. She hits the cue ball hard out of frustration, but the cue ball crawls across the table slowly. Bob shrugs his shoulders and goes off to get another round. Orders two pints and two shots and returns a good while before the cue ball finishes its trip across the table. When the cue ball finally strikes the 4 ball both of the balls move as if the cue ball had been traveling at a good clip.
Alice drops the pool cue and looks at Bob, fed up, and ready to leave.
Bob stops her before she can say anything "I'll tell you what. Flip a coin. If you win I'll leave you alone, you can go home and tell everyone that I rigged the table. But... If I win you have to take this shot and hear me out."
Alice furrows her brow digs in her pocket and produces a quarter. She pauses for a moment and flips it into the air. "Call It!"
Sure enough, the quarter bounces onto the table rolls on its edge in a circle around the shot glasses and just stops. Still standing on its edge.
Alice's eyes open wide, and without saying anything, she grabs a shot glass, downs the whiskey, and slams the glass upside down, trapping the still standing quarter.
Bob takes his shot, slowly knocks it back, and starts to explain...
"So... I was messing around in the garage the other day..."