Someone who is extraordinarily adept at sexual intercourse and all things pertaining to it, such as cunnilingus, erotic massage and vaginal or anal penetration (Accomplished by either penis or artificial phallus)
Often graced with "Lucas" as either their first or second name.
Also generally the meaning implied when the word "Beast" is used to describe how someone performs sexually.
Can also commonly be considered akin to definition #1 of Sexy Beast
"Lucas is a Sechs Beast"
Archaic: "She gives head like Beast"