You'd be hard-pressed to find rubber pants that allowed themselves to be formed around an erection AND allowed themselves to be worn during penetration.
To say the least.
Condoms are not made of rubber. They are made of latex (or polyurethane). It isn't just the containment but the latex itself which helps prevent the spread of STDs and STIs.
So, even if what you're imagining were out there, using a latex condom for ALL genital and genital/oral contact provides as much protection as anything can, save being completely celibate.
Editor and Founder, Scarleteen
My epitaph should read: "She worked herself into this ground."
-- Kay Bailey Hutchinson