Once I saw a woman get off a bus and I thought she said 我下一下 to inform the driver that she was getting off. However, I mentioned that to a Chinese friend, and he seemed to think it's weird, so it's possible I misheard.
It's normal to say things like 我坐一下 or 我百度一下, where 一下 emphasizes that it would be quick; there are other examples in the Chinese Grammar Wiki article Verbing briefly with "yixia" (see also the question When to use "一下儿"). So I don't see any reason why 我下一下 would be improper.
Question: Is it okay to say 我下一下 when e.g. getting off a bus?