[header] How to tell your parents you have a girlfriend [title] Drop hints; talk about her. [step] Talk about your girlfriend as you would any other friend. This in itself that may lead them to figure it out. 
This can also be a way to get them more comfortable with the idea of you hanging out with girls (if that is not something you have done much before) or having a girlfriend. You can say something like this : [substeps] " my friend jessica and i are going to the movies tonight..." " oh, jessica's giving me a ride to the party.