No. You may not borrow against it or pledge the funds in it.
If you borrowed from your HSA account for non-qualifying purchases and later "replace" the money in your HSA account, you may be subject to tax penalties on the ineligible amount withdrawn when filing your taxes.
Here’s the rule on distribution mistakes: HSA distributions that are made by mistake can be returned to the HSA if there is clear and convincing evidence that the distribution was made “because of a mistake of fact due to reasonable cause.”
In other words, if you thought something was a covered medical expense but it turned out it wasn’t. If you thought botox was an eligible expense but later found out it wasn't, this would be a reasonable mistake. Using your HSA to buy alcohol (beer, rubbing alcohol could warrant an argument), there is almost no getting out of that one should you get audited.
For more information on prohibited activities, see Section 4975 of the Internal Revenue Code.