A bicep slicer is a submission hold that attacks the bicep muscle of your opponent...
Most big BJJ organizations like the IBJJF have banned the bicep slicer from their competitions...
Another easy bicep slicer from on top in side-mount is the same side bicep slicer. Coming off of a pseudo crucifix that is quite painful..
You can even hit a bicep slicer from the back that is extremely easy to hit...