2.4 Prop Abuse - The use of a prop to kill, push, or surf entities is not permitted.

4.15 Building Signs - A building sign can only be used on a house in which you're building in at the time. You can't have any entities which includes health/armour chargers. Anything similar to "Building" will be counted as a building sign so you shouldn't use fake signs to try "Tricking" people. You're not allowed to place building signs on houses you don't own.