Two things you could do. As someone else mentioned above say it was some sort of issue with your phone because it has been acting very strange lately. Or, just tell them the truth lmao. Say you have been getting repeating spam calls and decided enough was enough and that you were sick of it so you started messing with them. Honesty, even in really awkward situations like that can go a surprisingly long way. You can laugh it off with them, show them that you can act professional and I’m sure they would appreciate that. Then it can be something you laugh over hopefully without getting some sort of nickname (I.e. thunderguts or something like that) but honestly if you want to keep pursuing a job there I think an honest explanation or if you want a good excuse about your phone acting could be a good way to keep moving forward. Never give up keep pursuing if that’s what you want to do. I think being honest would be the best course though because it’s honestly hilarious and if you can be serious at work and do funny shit like that out of work those are the best kinds of people.