I think I might have groped someone and I feel awful about it.
Why did you grope someone ?
I was drunk and I have some fuzzy memories of it happening.
I'm sure you didn't mean to grope someone when you were so drunk but you need to learn more about the incident. Ask others that were present if they remember if you did grope someone and have them confirm that. If it's true, you need to find the person you groped and ask for forgiveness.
I'm not going to do that, I don't remember anything about it.
How would you feel if someone groped your family member?  You did an awful thing and you need to apologize.