Some city buses will begin carrying advertisements next month asking sex partners to "play safely" as a way to avoid being stricken by acquired immune deficiency syndrome (AIDS), despite fears that the ads will offend riders. The ads will appear in 80 Rapid Transit District buses beginning in June. The RTD originally refused to carry the ads but changed its mind after months of negotiations with L.A. CARES, the state-funded group sponsoring the ads. The ads feature an actress portraying a mother wearing an apron and holding a wooden spoon while saying, "Play Safely." Below is a caption which reads, "L.A. CARES . . . like a mother."