From advice reddit sub:

/r/Advice/comments/bgtm13/my_little_cousin_7f_is_joking_about_me_flashing/ r/AdviceFamily My little cousin [7/F] is joking about me flashing her u/throwaway48296

My cousin and I get along really well she's the sweetest girl and I'm unemployed at the moment so I baby sit her for my older cousin for free because I just enjoy her company. I was talking to her while she was playing Minecraft and she asked if she could sleep in my bed. I said no she should sleep in one of the rooms inside because I stay up really late most of the time. She said "I stay up really late sometimes too but its a secret so don't tell mom", I said I'm gonna tell her as a joke then she said "no you can't otherwise I'll tell mom your secret" and I asked her what was my secret? She paused and thought for a second and said "that you showed me your doodle" and then she giggled like she was telling a joke but I'm quite shaken up that she will not realise the repocussions of saying this like that especially with the amount for time we spend together. I've got no clue how I should tackle this or if I should just try to brush it off

TL;DR cousin saying I showed her my penis as a joke and I'm not sure how to handle this