There are two methods
A.) the safest and more proven way to have a longer banana is mirco-tearing. The basic premise is when a guy's dick is stretched enough to "scar" the penile tissue, their body naturally tries to heal the surrounding area, thus leaving him a longer dick. You can achieve this by Jelqing* or using a Phallosan** (Several people have reported that Bathmates improved their girth) .
Cons: As you might imagine, this takes forever to get decent gains because of how slow the body heals under normal conditions. This method also doesn't give you new nerves rather span them out, so it can potentially make sex less fun.
B.) The more risky method. Would applying Testosterone cream or DHT cream*** on the benis help obtain penile or clitoral growth? It doesn't work unless the participate uses a supplement that upregulates their androgen receptors. One should take a peptide to up-take their androgen receptors to somewhat simulate puberty**** (an aspect of it), like IGF-1, to fix that. Then this shall work. (however, you must cycle).
Cons: For most countries, it's illegal to consume peptides or T-cream unless you have been approved by the government. This hasn't been proven on otherwise healthy people. What we do know about individuals with high DHT/Testosterone is that; they're more prone to prostate cancer, live shorter lives, and develop male-patterned baldness. And this is likely why doctors don't prescribe this to their patents, it's too dangerous. altho, it's your life I guess.
*
http://vkool.com/how-to-do-jelqing/**
http://www.phallosan.com/fileadmin/doc/PHALLOSAN-clinical-study-en.pdf***
https://www.ncbi.nlm.nih.gov/pubmed/7361738 https://www.ncbi.nlm.nih.gov/pubmed/660741/ ****
https://www.jurology.com/article/S0022-5347(01)64400-8/fulltext 