BAMF means "Bad Ass Mother F***er". The Y- at the end means "Like a". Altogether, "Like a Bad Ass Mother F***er"
Thomas Jefferson, defender of the second amendment and founder of the United States of America, is bamfy.
Bamfy can't be defined. It is a state of mind that transcends all lamfy-ness. But in case you're not bamfy enough to just get that (which is nothing to be ashamed of, few ever earn the honorable distinction of "bamfy"), the word is the adjective form of BAMF, meaning "Bad Ass Mother F***er". Among the ranks of the bamfy are the Dos Equis spokesman, David Tennant, and Chuck Norris. Oh yeah, and Mother Teresa. What a bamf.
The Doctor just saved the world for the bazillionth time and finally walked away from that lamfy Martha chick. What a bamfy bamf.