I don't think tunnelling is a performance thing... it isn't part of any competitive swimming that I know of. I do know that swimmers who show butt crack at a swim meet will be asked to fix that. We want to keep it PG. The rules call for appropriate swim wear, the meet referee is in charge of defining that. And they do! You know, there is a time and a place for exhibitionism, but teens doing it around little kids is not going to be allowed at a USAS event, trust me..
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