Can you get itp (idiopathic thrombocytopenic purpura) from being around a person who has it? Is it contagious?

Not contagious. Itp is an immune-mediated process that leads to a very low platelet count. It is not a contagious condition that you can get from being around somebody with the disorder.
No. Itp is considered an autoimmune or post viral immune process. In either case the problem is an immune response that causes platelet destruction. Immune responses are not contagious.