I'm playing a board game with my 97 year old grandmother and I'm going to lie to her while doing it.
What makes you want to lie and hurt your grandmother?
It's something that happens often. She's really old and she'll die soon. I don't give a shit about her.
You should take care of your grandmother and enjoy her presence while she's still alive. It isn't right to cheat in a game with someone because they're elderly.
Fuck you, my grandma is old anyway. I want to enjoy my time with her and making her feel bad allows that for me.
Making another person feel bad isn't a good way to feel pleasure. I'd suggest looking inward and seeing why you feel that way instead of being mean to an elderly person. How are you going to feel when she's gone and your memories are of lying to her?