If you're in charge of the company, you can authorize expenditures for anything that reasonably relates to the company's business, including attracting investors, retaining employees, or incenting them to succeed. It's reckless to spend all your money on parties, but not illegal.

But if you authorize the company to spend money on something which is in itself illegal (cocaine or weed for the parties, hookers instead of strippers), that's illegal. And if you effectively direct the money to your own benefit (pay for your house's landscaping, new pool, pet grooming bill) that's not legal (among other things, it counts as taxable income and I bet you forget to pay on that).