Generate a sentence using the idiom "stealing someone's thunder".
After months of planning her friend's surprise birthday party, she was disappointed when someone else announced it first, stealing her thunder.
Complete the following task based on the instruction and optional input provided.### Instruction:
Generate a sentence using the idiom "stealing someone's thunder".

### Output:
After months of planning her friend's surprise birthday party, she was disappointed when someone else announced it first, stealing her thunder.