My girlfriend get home late and for her punishment I tickle her in the garage. Is that wrong for me to do?

Well I tell her to come home at 9 Pm. She comes home at midnight. I know how ticklish she is an we go to the garage and I tie her up. I tickle her for 45 minutes, and than I stop until she promise to me that she will be home 9 Pm. Some times I tickle her for an hour almost everyday. This is her punishment when she argues with me or when she does something I don't like.