Perhaps the most obvious birthday celebration idea ever, but for a reason. The house party has been with us for a long, long time and offers those who opt for it a familiar surrounding coupled with (mostly) familiar people and as crazy time as they wish. Whether you go for sophisticated champagne and canapé type affair or loads of booze and a metal band, there is much fun to be had with this option. Another pro is budget, having a house party is one of the cheapest ways to celebrate your 21st Birthday. So whether you’re a struggling student or just don’t have all that much money to blow, a house party might be the choice for you.