Is it acceptable to ask for advice about putting together sci-fi related costumes on this site? I'm really itching to go to a Halloween party after work this Friday as a Centauri, but can't figure out how to get my hair to stand up!
I think that it is off-topic, as much as I don't want it to be. It's really a hair styling question, despite it's sci-fi leaning (like how asking about training to be a snitch in Quidditch would really be a Fitness question; also SOMEONE PLEASE ASK THAT). BUT as someone who also spends way too much time on Halloween costumes, I sympathize with the dilemma and wish there was an SE for it. I figure the least we can do is try to answer it here in Meta (or the least I can do).
I think you should Google tips for creating big mohawks. From what I've seen of Centauris, it looks like the creation process could work similarly. Here are some links about creating mohawks: here or here. I did a Google search specifically for Centauri costume tips and came up empty-handed. I hope this helps some!
I also hope that other people disagree with me saying that this is off-topic, because I also love Halloween and have a million costume questions.
I think a question on how to design a costume with an SF theme would be on-topic here. For example, “what is a reasonable hairstyle for a Centauri disguise that I can make at home”.
But the question you ask is only tangentially related to SF, and crucially, the expertise to answer your question is not at all related to expertise. How to get your hair to stand up is a question for a make-up expert or a hairdresser, not for an SF expert. So this question is off-topic here.