To whoop it up means to celebrate, especially with cheers and whoops, and that is exactly what the others continued to do.
Context: "By midnight, mia was feeling the effects of the alcohol, and she slowed her intake while the others continued to celebrate loudly and enthusiastically."
Hypothesis: By midnight, mia was feeling the effects of the alcohol, and she slowed her intake while the others continued to whoop it up.
Based on the context, is the hypothesis true, false, or unknown?