Yeah, the key is walking around the entire night with your arm bent and at a level where your bicep is under maximum tension for the night
Ways of making this look like it's not intentional is:
1) A pint in hand
2) Giving directions
3) Pointing at something funny (if nothing available, make something by putting something slippery like grease on some stairs)
4) Doing an impression of a T-Rex
5) Doctors orders
Also, taking 30 minute breaks to go in a toilet cubicle and do push ups will help maximise the effect
Hand positioning is key too, if you have short insertions, be careful about turning your hands with the palms facing the ceiling, as this will give you an unattractive gap, but on the flipside will give maximum peak, so if you have a short enough t shirt it might be worth the risk.