I sent my parents a text message with an image of the tattoo that I am planning to get on the 2nd. Technically I am an adult and can do whatever I want, but since I live with them, I try to take their wishes into account.
Communicating by text with my parents is how I usually bring up difficult topics.
I think my Dad will be fine with it but I can guarantee my Mom won't be happy.
I usually call them on my lunch break....in about half an hour, so I might get an earful then!