Saying something very soppy such as ‘Who Loves Ya, Poo?
I'll tell you, I do, Fozzy bear, that's who!'
You'd entirely fail to charm me, in fact I'd detest it
I wouldn't be eighteen again for anything, I'm glad I'm past it.
I wouldn't thank you for a Valentine.
If you sent me a single orchid, or a pair of Janet Reger's
In a heart-shaped box and declared your Love Eternal
I'd say I'd rather not be caught dead in them they were
Politically suspect and I'd rather something thermal.
If you hired a plane and blazed our love in a banner across the skies;
If you bought me something flimsy in a flatteringly wrong size;
If you sent me a postcard with three Xs and told me how you felt
I wouldn't thank you, I'd melt.
The last line is open to interpretation. One possibility is that the gifts in the last stanza would strike a chord and the speaker would find these acceptable, although this is unlikely; they don’t differ that much in uselessness from the preceding gifts. 
 Another suggestion is that the speaker would “melt” with embarrassment, though there is insufficient evidence in the poem for this. 
 More likely is that she is receptive to the love that prompted the gifts, though not the gifts themselves.  It is this underlying love that she appreciates, so they cause her to “melt”.  The poem concludes with the idea that it is love that is important, not the commercialisation and material gifts.
I Wouldnt Thank You For A Valentine