Well,

petabecquerel,
petaflops,
pferdestärke,
pfund,
phot,
picofarad,
picolo,
picomole,
picotesla,
pieze,
plethron,
poiseuille,
poncelet,
pottle,
pud,

are all names for various measurements that begin with P. And I don't find any of them to be really pleasant for pontification.