My Dad is very challenging at the moment. I do try to laugh at it, as much as I can (if you don't laugh, you'll cry).
Recent examples are :
My Mum was very ill. Someone had to go the the hospital to discuss her prognosis. My Dad is scatty, hard of hearing and not on the ball whatsoever, so we suggested that me and my sibling should go to the meeting, but Dad was adamant, that as the "man of the house", he should go. So we said to him "Okay, but you must take a pen and paper, write everything down and be as sharp as a tac", to which he replied "what's that about a shark attack?" Needless to say, we went instead of him!
My DH's great grandparent, frequently got the TV remote confused with the remote for the garage door. Cue much confusion as to why the channels weren't changing, however, the garage door would be going up and down constantly.