Definition
There appears to be no widespread or formally recognized botanical term "bouncing bess." It is likely a regional or colloquial variant of "bouncing bet" (Saponaria officinalis). If referring to 'bouncing bet', it shares the same soapy qualities due to saponins. This allows a mild lather when agitated in water. Similar to discovering a natural cleaning agent. It may also be a nickname within certain communities. Thus, clarifying the context is important when you see this name.