A bit annoyed

[bigplayer]

Splits with "F"

Was also told that you never split any cards that start with the letter "F"

The old saying is never split cards that start with "F". Fours, Fives, and Frickin Tens. Like many old sayings it's only partially correct for basic strategy players. (games that don't allow double down after splits). If you can double after your split you should split 4's vs 5 and 6.