The best thing I can tell you is to submit a Webform attaching information on the source of the cash. For example, I had an Investment fund with around 15K, we transferred most of these to our joint account, so the monthly balance (avg.) was 1500K, but all of the sudden there are 20K in this account. So when we submitted AOR we added a LoE explaining where the money had come from and tha bank letter that said that I had that investment fund under my name. Additionally, I provided my checking account in POF with a letter of no objection for her to have access to this money.
In your case 2 things can happen:
- They catch on this and nicely ask you ADR to prove the source
- They reject your application based on a non-justified, non-explainable source of high volume cash
If you create a WebForm and submit and they haven't caught up on this, they may get the alarm that something is off, if not, the officer may have just gone over it and accepted it as ok.
It will sound sketchy that your friend just gave you money, in this case, if you want to provide proof of this, he has to write a letter (notarized affidavit) in which he explains under the circumstances he is giving you this money and state that the money is yours to do as you please with it.
