Why do i randomly get imed on yahoo?

Recently in the past couple months I've been getting random ims from people or computers.They say one thing like "axnas 15 houjgs" or "meeevxib hyytgjk" not even real talk. I ask them who they are an i sometimes insult them and they never respond so I block them. I look at their info and theres no picture and it just says their gender and where they're from but nothing else. Its a yahoo messenger profile. Has it happened to anybody before and do you know why?