Raspberry Jam - A skirmish, typically close-quarters between two relatively equally armed forces. Notable casualties on both sides. Often, the strength of one side (usually defensive) isn't expected by the other (usually offensive). This underestimation usually puts a side, or both in a tight spot they may not be equipped for. Hence the jam.
*SWAT forces storm a location, but don't expect their opposition to have fully-automatic weapons. After a bloody firefight with casualties on both sides, one agent remarks to the other:*
"One hell of a raspberry jam we got ourselves into, eh?"