The waiter, identified as Martin D., 21, told the Bild newspaper he was bringing the beer to Merkel's table at the Demmin Christian Democratic Union meeting in Mecklenburg last Wednesday because a female coworker was too nervous to serve the head of state's table, The Local reported Tuesday.
"I was shoved from behind, and tried to catch the beers, but it was too late. I shouted (expletive) really loudly," he said.
The waiter said Merkel kept her cool and didn't scold him for the spill or his foul language.
"She turned around, grinned at me -- and even though she was wet, went to the speaker's stage shortly afterwards," he said.
Video of the beer being dumped down the chancellor's back has become popular on YouTube, with one posting accumulating nearly 600,000 views as of Tuesday.