... asking for a friend ☺.  Trying to make a new friend and getting *some* mileage out of Spanish/English translation sites, but I don't know if "arriba" or "versátil" are the appropriate terms in our context.
I think that "activa/activo" and "pasiva/pasivo" are common?  So would "Tu activa -  Yo pasivo" get the basic sense of "Please fuck me with that big beautiful cock" across?
Thanks!

In the realm of sexual relations, "active" can refer to the person penetrating another, while "passive" can refer to the person being penetrated.

"Por favor fóllame con esa gran y hermosa polla, bebe"