Most every professional golf tournaments on the world's greatest tours has sponsor exemptions and/or open qualifiers who are in the field. They're frequently not regulars and lack status on these major tours, but they're given or play their way into a special opportunity.
However, on the LPGA Tour, taking on an exemption or invitation, or getting in the field through open qualifying has a (slight) risk. The LPGA Tour expects players competing in their fields to be competent enough to break 88 in their rounds in an official LPGA event. In fact, they think that's so important that they've put a rule in place which punishes players who cannot do that.
Colloquially referred to as Rule 88 on the LPGA Tour, the policy applies to non-members of the LPGA competing in their sanctioned events. If a player shoots 88 or worse in a sanctioned round, that player is then banned from competing on the LPGA in any capacity for the remainder of the season. On top of being barred for the rest of the season, a player cannot complete the tournament in which they shot 88 or worse.
In the LPGA's Q-School system, the 88 rule also applies. Any player with a score of 88 or higher in any of the first three rounds of any stage of Q-School is automatically be withdrawn from the Qualifying Tournament and will not be eligible to receive any type of Tour status for that next year.
The most notable case in which Rule 88 was nearly applied was in July 2007, when Michelle Wie, playing on a sponsor invitation, was in danger of shooting 88 at the Ginn Tribute at RiverTowne Country Club in Mount Pleasant, S.C. She was 14 over par through 16 holes on the par-72 course, when she decided to withdraw with two holes to play. She was 17 years old at the time.
At the time, Wie said she wasn't thinking about Rule 88 and the potential impact on the remainder of her year. Wie cited a wrist injury, which has actually proven to be a chronic problem throughout her career, as the reason for the withdrawal. However, LPGA chief operating officer Chris Higgs spoke with Wie's agent, Greg Nared, just moments before the sudden withdrawal, suggesting there was a hint given of what could happen.