muss
Longman Dictionary of Contemporary English 5++LDOCE 5++muss1 /mʌs/ (also muss up) verb [transitive] informal especially American English UNTIDYto make something untidy, especially someone’s hair 把〔某物，尤指头发〕弄乱，使凌乱 Briscoe reached down and mussed the boy’s hair. 布里斯科伸出手揉了揉那男孩的头发。→ See Verb table
Examples from the Corpus
muss• He never got his hair mussed.• Pre-Hugo, come to think of it, my hair never got mussed.• Grass long and mussed by wind.• The store man Alexander headed them, stepped toward the boy Earl Varney and mussed his hair.• The other was mussed, the bedspread pulled down and the pillows stacked against the headboard.• A warm breeze mussed up her wispy hair.muss2 noun no muss, no fussno fuss no muss used to say that something can be done easily and without problems – used humorously 很容易，没问题〔幽默用法〕 It works every time, no muss, no fuss. 它每次都奏效，没有任何问题。Examples from the Corpus
muss• No fuss, no muss and no need for professional advice.• What Dickie likes is no muss, no fuss.• No muss, no fuss, just good old displacement.Origin muss1 (1800-1900) Probably from messmuss1 verbmuss2 nounChinese
someone’s make especially Corpus to untidy, something hair
muss
muss1 /mʌs/ 
(also muss up) verb [transitive] informal especially American English
Briscoe reached down and mussed the boy’s hair.
muss2 noun
no muss, no fuss used to say that something can be done easily and without problems – used humorously:
It works every time, no muss, no fuss.
| I |
(also muss up) verb [transitive] informal especially American English Date: 1800-1900
Origin: Probably from mess
to make something untidy, especially someone’s hair:Origin: Probably from mess
| II |
nounno muss, no fuss used to say that something can be done easily and without problems – used humorously: