It’s an act of good faith that could turn ugly: lottery pools.

Ahead of Tuesday’s $1.6 billion (yes, billion) Mega Millions drawing, many people around the country are sharing their lottery dreams with co-workers and pitching money into office pools to buy tickets. But as with all activities involving money, experts warn there are ways lottery pool winners can prevent a case of who-owes-what from heading into court.

“Money often comes between the closest of friends and even family members. When you couple that fact with about 10 added zeros, the emotions can only be hardened,” said Rubin Sinins, a lawyer who has consulted various individuals on questions of lottery pools.

The lawyer said "camaraderie" can make participating in an office pool worth it, but says it's best to first establish some ground rules.

“You have to be crystal clear about who is part of the pool and document for everyone involved who is part of the pool,” said Sinins, who represented five New Jersey construction workers back in 2009 over a $38.5 million lottery pool dispute.

The construction workers said a former co-worker was lying when he claimed sole ownership of the ticket. A state court ended up resolving the dispute in 2012 after making Americo Lopes, the defendant in the case, give each of the participating workers $4 million out of the $24 million cash option.

The construction workers aren't the only example of this. John Piccolo was sued by his hospital co-workers after refusing to share the $175,000 he claimed he won in a 2004 Mega Millions lottery.

Indeed, some office pools have even been successful recently, with 11 co-workers in Santa Clara, California, sharing the $543 million Mega Millions prize in July.

“Lottery pools are great way to play,” said Carole Gentry, managing director of communications for Maryland Lottery and Gaming. “It’s fun to talk about it with your friends, your family. It's great fun.”

But like, Sinins, Gentry also emphasized the importance of documenting who gets what.

“If you are going to do a pool, typically get a person who is in charge,” Gentry said. “If they are smart about it, they have each person write their name down.”

Gentry said the popularity of office pools only grows when jackpots grow. Even Sinins' office will be participating in a pool in Tuesday's record drawing — with a clear set of rules, of course.