“I wish I didn't have that stray hair sticking out.”
You're looking at vacation photos with your husband. There's one photo which has a beautiful background, but there's a problem with your hair. You complain about it.
I wish I didn't have that stray hair sticking out.
When you use the phrase "I wish ___" to talk about things that you would like to be different, use the past tense instead of present tense:
I wish I wasn't so thin.
I wish I knew how to help you, but I don't.
If you ever need to wish about something that happened in the past, you use past perfect tense:
When some of a person's hair isn't in the right place, you can call it "stray hair":
You have some stray hair sticking out over there.
Other things that can be "stray", meaning not in the right place, include:
a stray bullet