Tax Exempt Status

I was reading that members should/should not do some things in order to protect the "tax exempt status" of the church. The website provides the following list of things to avoid doing in order to protect the tax exempt status:

Wards must not:

1-) Rent out meetinghouses or parking lots.
2-) Rent out meetinghouses for events such as wedding receptions and reunions. Members may use meetinghouses at no cost for these kinds of events.
2-) Use Church property for the sale of commercial items or for any commercial purpose.
4-) Conduct unauthorized fund-raising activities on Church property.
5-) Advertise social events to the general public and charge admission.
6-) Have a mandatory charge to any social activity.

Specifically regarding number 6 above, does this mean that quorums and auxiliaries should not ask members of the group to supplement the cost of an activity with personal funds? For a hypothetical example, if a quorum of priests go to watch an athletic event together, is it okay for each member to pay a portion of the cost out of their own pockets and have the ward/branch supplement the remainder of the cost from the Young Men budget?....Or would that scenario put the church in jeopardy of losing its tax exempt status?

I'll answer your question from a different angle: Handbook 2: 13.2.8 - Funding for Activities.

Stake and ward budget funds should be used to pay for all activities, programs, and supplies. Members should not pay fees to participate. Nor should they provide materials, supplies, rental or admission fees, or long-distance transportation at their own expense.

It goes on to spell out exceptions, but that's not one of them.