1) Caddishly 2) How lowlifes operate 3) In a despicable way 4) In a dishonorable manner 5) In a dishonorable way 6) In a low way 7) In a lowdown way 8) In a mean way 9) In a nasty way 10) In a servile manner 11) In a snide manner 12) In a vulgar way 13) In an ignoble manner 14) Meanly 15) No way to behave 1) Scurvily 2) Squalidly 
• (adv.) Illegitimately; in bastardy. • (adv.) In a base manner; with despicable meanness; dishonorably; shamefully.
Base'ly adverb 1. In a base manner; with despicable meanness; dishonorably; shamefully. 2. Illegitimately; in bastardy. [ Archaic] Knolles.