(Undated) -- Illinois State Police are alerting prom-goers to celebrate smart. Authorities want teens to avoid underage drinking because it is extremely dangerous. Troopers are also warning adults not to purchase alcohol for minors. Buying drinks for underage teens is a Class A misdemeanor and you could face fines, probation and possible time behind bars. Several high schools in Fulton County have already held their proms. Canton's is coming up this Saturday.