How do I get rid of this sh**?

How do I get rid of this sh**? I was just at a grocery store in the self checkout line waiting and the guy behind me kindly pointed out there was an open one next to us I turn to him to just say thank you and it took me like 5 or 6 tries to even get it out, and I hate that when I stutter I tend to make like a tsk sound at the beginning and I feel like it comes off so weird and I hate it and I got so embarrassed struggling to just say “thank you” 😩😭😭