In this◊ strip, Garfield keeps hearing a "Ding", but it's not until the end that he finds out a man from Ed's Dong Repair was testing their doorbell.
There's a The Far Side cartoon of a bunch of scientists watching a movie featuring a caveman skeleton and the title "IT CAME FROM OLDUVAI". The caption: "Anthro horror films." This obviously refers to anthropologists, but now it would indicate something very different.
'Making love' shows up at times in Krazy Kat, in what is probably the original sweet-talk sense, as opposed to the down-and-dirty one.
A strip in which Ignatz's ancestor, in love with Krazy's ancestor (a queen), is apprehended by her guards: "How dare he get gay with our sainted 'Kat'!" Since Krazy is not consistently female, well...
Many early Broons and Oor Wullie comics had characters using the word "Gey" (pronounced like "guy", but when written down...), a now-obsolete eastern Scottish word for "Very". It wasn't unusual for characters to remark: "That's gey queer" when something odd was up! Another strip in particular had Horace refer to Gran'paw as a "Deif auld faggot", "faggot" at the time in Scotland meaning something tired and/or useless.
In a September 1937 strip of Little Orphan Annie where Annie tells her foster parents, the Brittlewits, about three criminals who tried to kidnap her and two of her classmates we have a very nice example. What makes it extra funny is the way Mr. Brittlewit seems to be as aware of the trope as the readers are.
Annie: It was a snatch, all right. They tried to grab us all.
Mr. Brittlewit: What language! Is that what you learn in school?
The eponymous dog in the early 1908 comic written by Margaret Hays that ran in the Boston Herald Sunday comics section, Jennie and Jack, also the Little Dog Jap, has a name that would be considered a slur these days.
"Jap" back then was a moderately common name, a variant on "Jaap", a diminutive Dutch form of Jacob.