That depends on whether you are polite about it. "I don't like you, I wanna see Joe!" probably isn't going to get a good reaction. "Could I please talk to Bob?" is more likely to.
Some people actively like to be asked. Especially those who are trigger based and thus aren't necessarily able to switch without an external influence.
(Treating a person like "that other you" is generally a bad idea...)
(Keeping balance in how many times you ask for people. Some people may have problems always being asked.)
You ask for who ever can do the job that you can't do at the time to come to the front and do it. Simple.