This is urban slang, so it is not widely used in regular conversation. Definition from the Urban Dictionary: To be jumpy or anxious to do something. Most commonly it refers to situations involving fighting or violence, but it can also refer to any situation involving someone anxiously wanting to do something. For example: Johnny was feeling froggy, so he drove to the city to find something to do.

"Are you feeling froggy? Then leap!" I hadn't heard of this phrase until now, but from what I can tell it means "Are you ready to do this? Then let's go!" The two examples the appeared most often were between two people who were ready to fist fight, or two people who ready to "get intimate."