A merry Snap

A merry Snap [prob of knapa (Saxon) a boy, because they are commonly merry]
a merry fellow.

Definition taken from The Universal Etymological English Dictionary, edited by Nathan Bailey (1736)

Snake [Hieroglyphically] * Snow
Shittenˊerdes
Shortness
Chain-Shot
Round-Shot [in Gunnery]
Cross-bar Shot
Case-Shot
Langrel Shot
Trundle Shot
Sin
Snake [Hieroglyphically]
A merry Snap
Snow
Speeks [with Shipwrights]
To Spitch-Cock an Eel
Spelter
Stang
Staˊnza [in Poetry]
Falling Stars
Fixed Stars
Stimulaˊtion
Striˊdent