Some things to do for a 19th birthday are to have a theme party, go camping with friends, posh celebration, pool party, or a meal out with friends. There can be other ways to celebrate that last teen birthday, such as a costume or movie marathon party.
Some ideas for a theme party can be a specific music era, such as the '60s or '70s, Hawaiian luau, fiesta, or movie theme. A costume or movie marathon party can be combined with '70s theme or movie theme, respectively.
If the celebrant is an outdoor enthusiast, then arranging a camping party with friends may be a fun idea. For a guy celebrating his 19th birthday, a toga party is another option that is popular with college age kids. However, if dressing up in formal wear seems appealing to the celebrant, then another idea for this momentous birthday can be to throw a posh party at a nice hotel.