1) Exasperating quip 2) Party game for linguists 3) Peter Piper 4) Peter Piper, etc 5) She sells seashells 6) Tricky phrase 7) Truly rural 
A tongue-twister is a phrase that is designed to be difficult to articulate properly, and can be used as a type of spoken (or sung) word game. Some tongue-twisters produce results which are humorous (or humorously vulgar) when they are mispronounced, while others simply rely on the confusion and mistakes of the speaker for their amusement value. F...
word or group of words made difficult to articulate by a close sequence of similar consonantal sounds. Tongue twisters are often passed on for ...
[n] - an expression that is difficult to articulate clearly
noun an expression that is difficult to articulate clearly; ``rubber baby buggy bumper` is a tongue twister`