The Drum
Scholars have said that seeing oneself transform into a drum may indicate engaging in disapproved actions. They also mentioned that the drum generally symbolizes scandals or vain businesses, while playing the tambourine may signify worries, calamities, or fame depending on the context.
Per Ibn Sirin's Muntakhab al-Kalam fi Tafsir al-Ahlam
Note: These are traditional scholarly interpretations (ijtihad) drawn from a specific classical source — not a binding religious ruling, fortune-telling, or a prediction of the future.