If you use the {{ FirstName | default: Friend }} clip, you may want to consider using the no profanity filter. The filter reviews data entered in the FirstName field against a list of common inappropriate words in English and French and will only show people's first names if they DO NOT contain any words from that list. Otherwise, it will show the default.
To use the clip, you can select the 'First Name (no profanity)' clip from the list of clips. More here.
This feature replaces the ‘commonize’ filter, which is no longer available in the clips menu. Ladders and other existing automated emails in your Group that use 'First Name, Commonized' will continue to work, checking FirstName values against a list of the most common names in the United States.